From 7ec5c31824bb3bffe9458e2c648323f7baa430ef 2014-06-15 06:26:00
From: Paul Ivanov <pi@berkeley.edu>
Date: 2014-06-15 06:26:00
Subject: [PATCH] more verbose message on missing jsonschema

---

diff --git a/IPython/nbformat/validator.py b/IPython/nbformat/validator.py
index e4bca09..38e8743 100644
--- a/IPython/nbformat/validator.py
+++ b/IPython/nbformat/validator.py
@@ -2,8 +2,17 @@ from __future__ import print_function
 import json
 import os
 
-from jsonschema import SchemaError
-from jsonschema import Draft3Validator as Validator
+try:
+    from jsonschema import SchemaError
+    from jsonschema import Draft3Validator as Validator
+except ImportError as e:
+    verbose_msg = """
+    
+    The `jsonschema` packages is now a hard dependency for IPython
+    
+    You can install it using `pip install jsonschema`
+    """
+    raise ImportError(e.message + verbose_msg)
 import jsonpointer as jsonpointer
 from IPython.utils.py3compat import iteritems