debug: add example of calling context

rhodecode/lib/utils2.py

@@ -319,6 +319,21 b' def find_calling_context(ignore_modules='
     this function and is part of core module ( ie. rhodecode.* )
 
     :param ignore_modules: list of modules to ignore eg. ['rhodecode.lib']
+
+    usage::
+        from rhodecode.lib.utils2 import find_calling_context
+
+        calling_context = find_calling_context(ignore_modules=[
+            'rhodecode.lib.caching_query',
+            'rhodecode.model.settings',
+        ])
+
+        if calling_context:
+            cc_str = 'call context %s:%s' % (
+                calling_context.f_code.co_filename,
+                calling_context.f_lineno,
+            )
+            print(cc_str)
     """
 
     ignore_modules = ignore_modules or []