detecting if a module is imported inside the app engine environment

What I want to do is patch an existing python module that uses urllib2 to run on app engine, but I don't want to break it so it can be used elsewhere. So I'm looking for a quick solution to test if the module is imported in the app engine environment or not. Catching ImportError on urllib2 might not be the best solution.

From stackoverflow

• You could simply use sys.modules to test if a module has been imported (I'm using unicodedata as an example):

  >>> import sys
  >>> 'unicodedata' in sys.modules
  False
  >>> import unicodedata
  >>> 'unicodedata' in sys.modules
  True