code: def testGetMissingReturnsNone(self, findConfigFile, environ):
      findConfigFile.side_effect = self.files.get
      environ.get.return_value = None
      configuration.Configuration.clear()
      result = configuration.Configuration.get(str(uuid.uuid4()))
      self.assertTrue(result is None)
  
imports: from copy import copy
  import os
  import shutil
  from StringIO import StringIO
  import sys
  import tempfile
  import unittest2
  import uuid
  from pkg_resources import resource_filename
  from mock import Mock, patch
  from pkg_resources import resource_filename
  from xml.parsers.expat import ExpatError
  import nupic
  import nupic.support.configuration_custom
  import configuration_test
label_desc: Use image node_id 22 for calling the ConfigurationCustomTest obj's underlying member method code with example usage: obj.testGetMissingReturnsNone(findConfigFile, environ) without return types