docs: def _load_resource_listing(resource_listing):
      """Load the resource listing from file, handling errors.
  
      :param resource_listing: path to the api-docs resource listing file
      :type  resource_listing: string
      :returns: contents of the resource listing file
      :rtype: dict
      """
      try:
          with open(resource_listing) as resource_listing_file:
              return simplejson.load(resource_listing_file)
      # If not found, raise a more user-friendly error.
      except IOError:
          raise ResourceListingNotFoundError(
              'No resource listing found at {0}. Note that your json file '
              'must be named {1}'.format(resource_listing, API_DOCS_FILENAME)
          )