code: def _load_credentials_file(credentials_file):
      
      try:
          credentials_file.seek(0)
          data = json.load(credentials_file)
      except Exception:
          logger.warning(
              'Credentials file could not be loaded, will ignore and '
              'overwrite.')
          return {}
  
      if data.get('file_version') != 2:
          logger.warning(
              'Credentials file is not version 2, will ignore and '
              'overwrite.')
          return {}
  
      credentials = {}
  
      for key, encoded_credential in iteritems(data.get('credentials', {})):
          try:
              credential_json = base64.b64decode(encoded_credential)
              credential = client.Credentials.new_from_json(credential_json)
              credentials[key] = credential
          except:
              logger.warning(
                  'Invalid credential {0} in file, ignoring.'.format(key))
  
      return credentials
docs: Load credentials from the given file handle.
  
      The file is expected to be in this format:
  
          {
              "file_version": 2,
              "credentials": {
                  "key": "base64 encoded json representation of credentials."
              }
          }
  
      This function will warn and return empty credentials instead of raising
      exceptions.
  
      Args:
          credentials_file: An open file handle.
  
      Returns:
          A dictionary mapping user-defined keys to an instance of
          :class:`oauth2client.client.Credentials`.