code: def _add_def_paths(self, prop_dict):
      
      for prop_key, prop_value in prop_dict.iteritems():
        if prop_key == '$ref' and not 'prop_value'.startswith('#'):
          prop_dict[prop_key] = '#/definitions/' + prop_dict[prop_key]
        elif isinstance(prop_value, dict):
          self._add_def_paths(prop_value)
docs: Recursive method to add relative paths for any $ref objects.
  
      Args:
        prop_dict: The property dict to alter.
  
      Side Effects:
        Alters prop_dict in-place.