code: def _ref(self, param, base_name=None):
          
  
          name = base_name or param.get('title', '') or param.get('name', '')
  
          pointer = self.json_pointer + name
          self.parameter_registry[name] = param
  
          return {'$ref': pointer}
docs: Store a parameter schema and return a reference to it.
  
          :param schema:
              Swagger parameter definition.
          :param base_name:
              Name that should be used for the reference.
  
          :rtype: dict
          :returns: JSON pointer to the original parameter definition.