Review and refactoring of notebooks web service.

IPython/html/services/notebooks/filenbmanager.py

@@ -1,361 +1,350 b''
 """A notebook manager that uses the local file system for storage.
 
 Authors:
 
 * Brian Granger
 * Zach Sailer
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import datetime
 import io
 import os
 import glob
 import shutil
 
 from unicodedata import normalize
 
 from tornado import web
 
 from .nbmanager import NotebookManager
 from IPython.nbformat import current
 from IPython.utils.traitlets import Unicode, Dict, Bool, TraitError
 from IPython.utils import tz
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class FileNotebookManager(NotebookManager):
     
     save_script = Bool(False, config=True,
         help="""Automatically create a Python script when saving the notebook.
         
         For easier use of import, %run and %load across notebooks, a
         <notebook-name>.py script will be created next to any
         <notebook-name>.ipynb on each save.  This can also be set with the
         short `--script` flag.
         """
     )
     
     checkpoint_dir = Unicode(config=True,
         help="""The location in which to keep notebook checkpoints
         
         By default, it is notebook-dir/.ipynb_checkpoints
         """
     )
     def _checkpoint_dir_default(self):
         return os.path.join(self.notebook_dir, '.ipynb_checkpoints')
     
     def _checkpoint_dir_changed(self, name, old, new):
         """do a bit of validation of the checkpoint dir"""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             abs_new = os.path.abspath(new)
             self.checkpoint_dir = abs_new
             return
         if os.path.exists(new) and not os.path.isdir(new):
             raise TraitError("checkpoint dir %r is not a directory" % new)
         if not os.path.exists(new):
             self.log.info("Creating checkpoint dir %s", new)
             try:
                 os.mkdir(new)
             except:
                 raise TraitError("Couldn't create checkpoint dir %r" % new)
-    
-    filename_ext = Unicode(u'.ipynb')
 
-    def get_notebook_names(self, path):
-        """List all notebook names in the notebook dir."""
+    def get_notebook_names(self, path='/'):
+        """List all notebook names in the notebook dir and path."""
         names = glob.glob(self.get_os_path('*'+self.filename_ext, path))
         names = [os.path.basename(name)
                  for name in names]
         return names
 
     def increment_filename(self, basename, path='/'):
-        """Return a non-used filename of the form basename<int>.
-        
-        This searches through the filenames (basename0, basename1, ...)
-        until is find one that is not already being used. It is used to
-        create Untitled and Copy names that are unique.
-        """
+        """Return a non-used filename of the form basename<int>."""
         i = 0
         while True:
             name = u'%s%i.ipynb' % (basename,i)
             os_path = self.get_os_path(name, path)
             if not os.path.isfile(os_path):
                 break
             else:
                 i = i+1
         return name
 
-    def notebook_exists(self, name, path):
+    def notebook_exists(self, name, path='/'):
         """Returns a True if the notebook exists. Else, returns False.
 
         Parameters
         ----------
         name : string
             The name of the notebook you are checking.
         path : string
             The relative path to the notebook (with '/' as separator)
 
         Returns
         -------
         bool
         """
-        path = self.get_os_path(name, path)
+        path = self.get_os_path(name, path='/')
         return os.path.isfile(path)
 
     def list_notebooks(self, path):
         """Returns a list of dictionaries that are the standard model
         for all notebooks in the relative 'path'.
         
         Parameters
         ----------
         path : str
             the URL path that describes the relative path for the
             listed notebooks
         
         Returns
         -------
         notebooks : list of dicts
             a list of the notebook models without 'content'
         """
         notebook_names = self.get_notebook_names(path)
         notebooks = []
         for name in notebook_names:
             model = self.get_notebook_model(name, path, content=False)
             notebooks.append(model)
         notebooks = sorted(notebooks, key=lambda item: item['name'])
         return notebooks
 
     def get_notebook_model(self, name, path='/', content=True):
         """ Takes a path and name for a notebook and returns it's model
         
         Parameters
         ----------
         name : str
             the name of the notebook
         path : str
             the URL path that describes the relative path for
             the notebook
             
         Returns
         -------
         model : dict
             the notebook model. If contents=True, returns the 'contents' 
             dict in the model as well.
         """
         os_path = self.get_os_path(name, path)
         if not os.path.isfile(os_path):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % name)
         info = os.stat(os_path)
         last_modified = tz.utcfromtimestamp(info.st_mtime)
         # Create the notebook model.
         model ={}
         model['name'] = name
         model['path'] = path
-        model['last_modified'] = last_modified.ctime()
+        model['last_modified'] = last_modified
         if content is True:
-            with open(os_path,'r') as f:
-                s = f.read()
+            with open(os_path, 'r') as f:
                 try:
-                    # v1 and v2 and json in the .ipynb files.
-                    nb = current.reads(s, u'json')
-                except ValueError as e:
-                    raise web.HTTPError(400, u"Unreadable Notebook: %s" % e)
+                    nb = current.read(f, u'json')
+                except Exception as e:
+                    raise web.HTTPError(400, u"Unreadable Notebook: %s %s" % (os_path, e))
             model['content'] = nb
         return model
 
     def save_notebook_model(self, model, name, path='/'):
         """Save the notebook model and return the model with no content."""
 
         if 'content' not in model:
             raise web.HTTPError(400, u'No notebook JSON data provided')
 
         new_path = model.get('path', path)
         new_name = model.get('name', name)
 
         if path != new_path or name != new_name:
             self.rename_notebook(name, path, new_name, new_path)
 
         # Save the notebook file
-        ospath = self.get_os_path(new_name, new_path)
-        nb = model['content']
+        os_path = self.get_os_path(new_name, new_path)
+        nb = current.to_notebook_json(model['content'])
         if 'name' in nb['metadata']:
             nb['metadata']['name'] = u''
         try:
-            self.log.debug("Autosaving notebook %s", ospath)
-            with open(ospath,'w') as f:
+            self.log.debug("Autosaving notebook %s", os_path)
+            with open(os_path, 'w') as f:
                 current.write(nb, f, u'json')
         except Exception as e:
-            #raise web.HTTPError(400, u'Unexpected error while autosaving notebook: %s' % ospath)
-            raise e
+            raise web.HTTPError(400, u'Unexpected error while autosaving notebook: %s %s' % (os_path, e))
 
         # Save .py script as well
         if self.save_script:
-            pypath = os.path.splitext(path)[0] + '.py'
-            self.log.debug("Writing script %s", pypath)
+            py_path = os.path.splitext(os_path)[0] + '.py'
+            self.log.debug("Writing script %s", py_path)
             try:
-                with io.open(pypath, 'w', encoding='utf-8') as f:
+                with io.open(py_path, 'w', encoding='utf-8') as f:
                     current.write(model, f, u'py')
             except Exception as e:
-                raise web.HTTPError(400, u'Unexpected error while saving notebook as script: %s' % pypath)
+                raise web.HTTPError(400, u'Unexpected error while saving notebook as script: %s %s' % (py_path, e))
 
         model = self.get_notebook_model(name, path, content=False)
         return model
 
     def update_notebook_model(self, model, name, path='/'):
         """Update the notebook's path and/or name"""
         new_name = model.get('name', name)
         new_path = model.get('path', path)
         if path != new_path or name != new_name:
             self.rename_notebook(name, path, new_name, new_path)
         model = self.get_notebook_model(new_name, new_path, content=False)
         return model
 
     def delete_notebook_model(self, name, path='/'):
         """Delete notebook by name and path."""
-        nb_path = self.get_os_path(name, path)
-        if not os.path.isfile(nb_path):
-            raise web.HTTPError(404, u'Notebook does not exist: %s' % nb_path)
+        os_path = self.get_os_path(name, path)
+        if not os.path.isfile(os_path):
+            raise web.HTTPError(404, u'Notebook does not exist: %s' % os_path)
         
         # clear checkpoints
-        for checkpoint in self.list_checkpoints(name):
+        for checkpoint in self.list_checkpoints(name, path):
             checkpoint_id = checkpoint['checkpoint_id']
             cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
-            self.log.debug(cp_path)
             if os.path.isfile(cp_path):
                 self.log.debug("Unlinking checkpoint %s", cp_path)
                 os.unlink(cp_path)
         
         self.log.debug("Unlinking notebook %s", nb_path)
         os.unlink(nb_path)
 
     def rename_notebook(self, old_name, old_path, new_name, new_path):
         """Rename a notebook."""
         if new_name == old_name and new_path == old_path:
             return
         
-        new_full_path = self.get_os_path(new_name, new_path)
-        old_full_path = self.get_os_path(old_name, old_path)
+        new_os_path = self.get_os_path(new_name, new_path)
+        old_os_path = self.get_os_path(old_name, old_path)
 
         # Should we proceed with the move?
-        if os.path.isfile(new_full_path):
-            raise web.HTTPError(409, u'Notebook with name already exists: ' % new_full_path)
+        if os.path.isfile(new_os_path):
+            raise web.HTTPError(409, u'Notebook with name already exists: ' % new_os_path)
         if self.save_script:
-            old_pypath = os.path.splitext(old_full_path)[0] + '.py'
-            new_pypath = os.path.splitext(new_full_path)[0] + '.py'
-            if os.path.isfile(new_pypath):
-                raise web.HTTPError(409, u'Python script with name already exists: %s' % new_pypath)
+            old_py_path = os.path.splitext(old_os_path)[0] + '.py'
+            new_py_path = os.path.splitext(new_os_path)[0] + '.py'
+            if os.path.isfile(new_py_path):
+                raise web.HTTPError(409, u'Python script with name already exists: %s' % new_py_path)
 
         # Move the notebook file
         try:
-            os.rename(old_full_path, new_full_path)
-        except:
-            raise web.HTTPError(400, u'Unknown error renaming notebook: %s' % old_full_path)
+            os.rename(old_os_path, new_os_path)
+        except Exception as e:
+            raise web.HTTPError(400, u'Unknown error renaming notebook: %s %s' % (old_os_path, e))
 
         # Move the checkpoints
         old_checkpoints = self.list_checkpoints(old_name, old_path)
         for cp in old_checkpoints:
             checkpoint_id = cp['checkpoint_id']
             old_cp_path = self.get_checkpoint_path(checkpoint_id, old_name, path)
             new_cp_path = self.get_checkpoint_path(checkpoint_id, new_name, path)
             if os.path.isfile(old_cp_path):
                 self.log.debug("Renaming checkpoint %s -> %s", old_cp_path, new_cp_path)
                 os.rename(old_cp_path, new_cp_path)
 
         # Move the .py script
         if self.save_script:
-            os.rename(old_pypath, new_pypath)
+            os.rename(old_py_path, new_py_path)
   
     # Checkpoint-related utilities
     
     def get_checkpoint_path(self, checkpoint_id, name, path='/'):
         """find the path to a checkpoint"""
         filename = u"{name}-{checkpoint_id}{ext}".format(
             name=name,
             checkpoint_id=checkpoint_id,
             ext=self.filename_ext,
         )
         cp_path = os.path.join(path, self.checkpoint_dir, filename)
         return cp_path
 
     def get_checkpoint_model(self, checkpoint_id, name, path='/'):
         """construct the info dict for a given checkpoint"""
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         stats = os.stat(cp_path)
         last_modified = tz.utcfromtimestamp(stats.st_mtime)
         info = dict(
             checkpoint_id = checkpoint_id,
             last_modified = last_modified,
         )
         return info
         
     # public checkpoint API
     
     def create_checkpoint(self, name, path='/'):
         """Create a checkpoint from the current state of a notebook"""
         nb_path = self.get_os_path(name, path)
         # only the one checkpoint ID:
         checkpoint_id = u"checkpoint"
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         self.log.debug("creating checkpoint for notebook %s", name)
         if not os.path.exists(self.checkpoint_dir):
             os.mkdir(self.checkpoint_dir)
         shutil.copy2(nb_path, cp_path)
         
         # return the checkpoint info
         return self.get_checkpoint_model(checkpoint_id, name, path)
     
     def list_checkpoints(self, name, path='/'):
         """list the checkpoints for a given notebook
         
         This notebook manager currently only supports one checkpoint per notebook.
         """
         checkpoint_id = "checkpoint"
         path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.exists(path):
             return []
         else:
             return [self.get_checkpoint_model(checkpoint_id, name, path)]
         
     
     def restore_checkpoint(self, checkpoint_id, name, path='/'):
         """restore a notebook to a checkpointed state"""
         self.log.info("restoring Notebook %s from checkpoint %s", name, checkpoint_id)
         nb_path = self.get_os_path(name, path)
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.isfile(cp_path):
             self.log.debug("checkpoint file does not exist: %s", cp_path)
             raise web.HTTPError(404,
                 u'Notebook checkpoint does not exist: %s-%s' % (name, checkpoint_id)
             )
         # ensure notebook is readable (never restore from an unreadable notebook)
         with file(cp_path, 'r') as f:
             nb = current.read(f, u'json')
         shutil.copy2(cp_path, nb_path)
         self.log.debug("copying %s -> %s", cp_path, nb_path)
     
     def delete_checkpoint(self, checkpoint_id, name, path='/'):
         """delete a notebook's checkpoint"""
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.isfile(cp_path):
             raise web.HTTPError(404,
-                u'Notebook checkpoint does not exist: %s-%s' % (name, checkpoint_id)
+                u'Notebook checkpoint does not exist: %s%s-%s' % (path, name, checkpoint_id)
             )
         self.log.debug("unlinking %s", cp_path)
         os.unlink(cp_path)
     
     def info_string(self):
         return "Serving notebooks from local directory: %s" % self.notebook_dir

IPython/html/services/notebooks/nbmanager.py

@@ -1,224 +1,224 b''
 """A base class notebook manager.
 
 Authors:
 
 * Brian Granger
 * Zach Sailer
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import uuid
 from urllib import quote, unquote
 
 from tornado import web
 
 from IPython.html.utils import url_path_join
 from IPython.config.configurable import LoggingConfigurable
 from IPython.nbformat import current
 from IPython.utils.traitlets import List, Dict, Unicode, TraitError
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class NotebookManager(LoggingConfigurable):
 
     # Todo:
     # The notebook_dir attribute is used to mean a couple of different things:
     # 1. Where the notebooks are stored if FileNotebookManager is used.
     # 2. The cwd of the kernel for a project.
     # Right now we use this attribute in a number of different places and
     # we are going to have to disentangle all of this.
     notebook_dir = Unicode(os.getcwdu(), config=True, help="""
             The directory to use for notebooks.
             """)
 
     filename_ext = Unicode(u'.ipynb')
 
     def named_notebook_path(self, notebook_path):
         """Given notebook_path (*always* a URL path to notebook), returns a 
         (name, path) tuple, where name is a .ipynb file, and path is the 
         URL path that describes the file system path for the file. 
         It *always* starts *and* ends with a '/' character.
 
         Parameters
         ----------
         notebook_path : string
             A path that may be a .ipynb name or a directory
 
         Returns
         -------
         name : string or None
             the filename of the notebook, or None if not a .ipynb extension
         path : string
             the path to the directory which contains the notebook
         """
         names = notebook_path.split('/')
         names = [n for n in names if n != ''] # remove duplicate splits
 
         names = [''] + names
 
         if names and names[-1].endswith(".ipynb"):
             name = names[-1]
             path = "/".join(names[:-1]) + '/'
         else:
             name = None
             path = "/".join(names) + '/'
         return name, path
         
     def get_os_path(self, fname=None, path='/'):
         """Given a notebook name and a URL path, return its file system
         path.
 
         Parameters
         ----------
         fname : string
             The name of a notebook file with the .ipynb extension
         path : string
             The relative URL path (with '/' as separator) to the named
             notebook.
 
         Returns
         -------
         path : string
             A file system path that combines notebook_dir (location where
             server started), the relative path, and the filename with the
             current operating system's url.
         """
         parts = path.split('/')
         parts = [p for p in parts if p != ''] # remove duplicate splits
         if fname is not None:
             parts += [fname]
         path = os.path.join(self.notebook_dir, *parts)
         return path
 
     def url_encode(self, path):
         """Takes a URL path with special characters and returns 
         the path with all these characters URL encoded"""
         parts = path.split('/')
         return '/'.join([quote(p) for p in parts])
 
     def url_decode(self, path):
         """Takes a URL path with encoded special characters and 
         returns the URL with special characters decoded"""
         parts = path.split('/')
         return '/'.join([unquote(p) for p in parts])
 
     def _notebook_dir_changed(self, name, old, new):
         """Do a bit of validation of the notebook dir."""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             abs_new = os.path.abspath(new)
             self.notebook_dir = os.path.dirname(abs_new)
             return
         if os.path.exists(new) and not os.path.isdir(new):
             raise TraitError("notebook dir %r is not a directory" % new)
         if not os.path.exists(new):
             self.log.info("Creating notebook dir %s", new)
             try:
                 os.mkdir(new)
             except:
                 raise TraitError("Couldn't create notebook dir %r" % new)
 
     # Main notebook API
 
     def increment_filename(self, basename, path='/'):
         """Increment a notebook filename without the .ipynb to make it unique.
         
         Parameters
         ----------
         basename : unicode
             The name of a notebook without the ``.ipynb`` file extension.
         path : unicode
             The URL path of the notebooks directory
         """
         return basename
 
     def list_notebooks(self):
         """Return a list of notebook dicts without content.
 
         This returns a list of dicts, each of the form::
 
             dict(notebook_id=notebook,name=name)
 
         This list of dicts should be sorted by name::
 
             data = sorted(data, key=lambda item: item['name'])
         """
         raise NotImplementedError('must be implemented in a subclass')
 
     def get_notebook_model(self, name, path='/', content=True):
         """Get the notebook model with or without content."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def save_notebook_model(self, model, name, path='/'):
         """Save the notebook model and return the model with no content."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def update_notebook_model(self, model, name, path='/'):
         """Update the notebook model and return the model with no content."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def delete_notebook_model(self, name, path):
         """Delete notebook by name and path."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def create_notebook_model(self, model=None, path='/'):
         """Create a new untitled notebook and return its model with no content."""
         name = self.increment_filename('Untitled', path)
         if model is None:
             model = {}
             metadata = current.new_metadata(name=u'')
             nb = current.new_notebook(metadata=metadata)
             model['content'] = nb
             model['name'] = name
             model['path'] = path
         model = self.save_notebook_model(model, name, path)
         return model
 
     def copy_notebook(self, name, path='/', content=False):
         """Copy an existing notebook and return its new model."""
         model = self.get_notebook_model(name, path)
         name = os.path.splitext(name)[0] + '-Copy'
         name = self.increment_filename(name, path) + self.filename_ext
         model['name'] = name
         model = self.save_notebook_model(model, name, path, content=content)
         return model
     
     # Checkpoint-related
     
     def create_checkpoint(self, name, path='/'):
         """Create a checkpoint of the current state of a notebook
         
         Returns a checkpoint_id for the new checkpoint.
         """
         raise NotImplementedError("must be implemented in a subclass")
     
     def list_checkpoints(self, name, path='/'):
         """Return a list of checkpoints for a given notebook"""
         return []
     
     def restore_checkpoint(self, checkpoint_id, name, path='/'):
         """Restore a notebook from one of its checkpoints"""
         raise NotImplementedError("must be implemented in a subclass")
 
     def delete_checkpoint(self, checkpoint_id, name, path='/'):
         """delete a checkpoint for a notebook"""
         raise NotImplementedError("must be implemented in a subclass")
     
     def log_info(self):
         self.log.info(self.info_string())
     
     def info_string(self):
-        return "Serving notebooks"
  No newline at end of file
+        return "Serving notebooks"

IPython/nbformat/current.py

@@ -1,226 +1,226 b''
 """The official API for working with notebooks in the current format version.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import print_function
 import json
 from xml.etree import ElementTree as ET
 import re
 
 from IPython.nbformat import v3
 from IPython.nbformat import v2
 from IPython.nbformat import v1
 
 from IPython.nbformat.v3 import (
     NotebookNode,
     new_code_cell, new_text_cell, new_notebook, new_output, new_worksheet,
     parse_filename, new_metadata, new_author, new_heading_cell, nbformat,
-    nbformat_minor,
+    nbformat_minor, to_notebook_json
 )
 
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 current_nbformat = nbformat
 current_nbformat_minor = nbformat_minor
 
 
 class NBFormatError(ValueError):
     pass
 
 class NotJSONError(ValueError):
     pass
 
 
 def parse_json(s, **kwargs):
     """Parse a string into a (nbformat, dict) tuple."""
     try:
         d = json.loads(s, **kwargs)
     except ValueError:
         raise NotJSONError("Notebook does not appear to be JSON: %r" % s[:16])
     nbf = d.get('nbformat', 1)
     nbm = d.get('nbformat_minor', 0)
     return nbf, nbm, d
 
 
 def parse_py(s, **kwargs):
     """Parse a string into a (nbformat, string) tuple."""
     nbf = current_nbformat
     nbm = current_nbformat_minor
     
     pattern = r'# <nbformat>(?P<nbformat>\d+[\.\d+]*)</nbformat>'
     m = re.search(pattern,s)
     if m is not None:
         digits = m.group('nbformat').split('.')
         nbf = int(digits[0])
         if len(digits) > 1:
             nbm = int(digits[1])
 
     return nbf, nbm, s
 
 
 def reads_json(s, **kwargs):
     """Read a JSON notebook from a string and return the NotebookNode object."""
     nbf, minor, d = parse_json(s, **kwargs)
     if nbf == 1:
         nb = v1.to_notebook_json(d, **kwargs)
         nb = v3.convert_to_this_nbformat(nb, orig_version=1)
     elif nbf == 2:
         nb = v2.to_notebook_json(d, **kwargs)
         nb = v3.convert_to_this_nbformat(nb, orig_version=2)
     elif nbf == 3:
         nb = v3.to_notebook_json(d, **kwargs)
         nb = v3.convert_to_this_nbformat(nb, orig_version=3, orig_minor=minor)
     else:
         raise NBFormatError('Unsupported JSON nbformat version %s (supported version: %i)' % (nbf, 3))
     return nb
 
 
 def writes_json(nb, **kwargs):
     return v3.writes_json(nb, **kwargs)
 
 
 def reads_py(s, **kwargs):
     """Read a .py notebook from a string and return the NotebookNode object."""
     nbf, nbm, s = parse_py(s, **kwargs)
     if nbf == 2:
         nb = v2.to_notebook_py(s, **kwargs)
     elif nbf == 3:
         nb = v3.to_notebook_py(s, **kwargs)
     else:
         raise NBFormatError('Unsupported PY nbformat version: %i' % nbf)
     return nb
 
 
 def writes_py(nb, **kwargs):
     return v3.writes_py(nb, **kwargs)
 
 
 # High level API
 
 
 def reads(s, format, **kwargs):
     """Read a notebook from a string and return the NotebookNode object.
 
     This function properly handles notebooks of any version. The notebook
     returned will always be in the current version's format.
 
     Parameters
     ----------
     s : unicode
         The raw unicode string to read the notebook from.
     format : (u'json', u'ipynb', u'py')
         The format that the string is in.
 
     Returns
     -------
     nb : NotebookNode
         The notebook that was read.
     """
     format = unicode(format)
     if format == u'json' or format == u'ipynb':
         return reads_json(s, **kwargs)
     elif format == u'py':
         return reads_py(s, **kwargs)
     else:
         raise NBFormatError('Unsupported format: %s' % format)
 
 
 def writes(nb, format, **kwargs):
     """Write a notebook to a string in a given format in the current nbformat version.
 
     This function always writes the notebook in the current nbformat version.
 
     Parameters
     ----------
     nb : NotebookNode
         The notebook to write.
     format : (u'json', u'ipynb', u'py')
         The format to write the notebook in.
 
     Returns
     -------
     s : unicode
         The notebook string.
     """
     format = unicode(format)
     if format == u'json' or format == u'ipynb':
         return writes_json(nb, **kwargs)
     elif format == u'py':
         return writes_py(nb, **kwargs)
     else:
         raise NBFormatError('Unsupported format: %s' % format)
 
 
 def read(fp, format, **kwargs):
     """Read a notebook from a file and return the NotebookNode object.
 
     This function properly handles notebooks of any version. The notebook
     returned will always be in the current version's format.
 
     Parameters
     ----------
     fp : file
         Any file-like object with a read method.
     format : (u'json', u'ipynb', u'py')
         The format that the string is in.
 
     Returns
     -------
     nb : NotebookNode
         The notebook that was read.
     """
     return reads(fp.read(), format, **kwargs)
 
 
 def write(nb, fp, format, **kwargs):
     """Write a notebook to a file in a given format in the current nbformat version.
 
     This function always writes the notebook in the current nbformat version.
 
     Parameters
     ----------
     nb : NotebookNode
         The notebook to write.
     fp : file
         Any file-like object with a write method.
     format : (u'json', u'ipynb', u'py')
         The format to write the notebook in.
 
     Returns
     -------
     s : unicode
         The notebook string.
     """
     return fp.write(writes(nb, format, **kwargs))
 
 def _convert_to_metadata():
     """Convert to a notebook having notebook metadata."""
     import glob
     for fname in glob.glob('*.ipynb'):
         print('Converting file:',fname)
         with open(fname,'r') as f:
             nb = read(f,u'json')
         md = new_metadata()
         if u'name' in nb:
             md.name = nb.name
             del nb[u'name']            
         nb.metadata = md
         with open(fname,'w') as f:
             write(nb, f, u'json')