code: def requires(self):
          
          # NOTE: spec says this can also be a list of strings
          value = self._schema.get("requires", {})
          if not isinstance(value, (basestring, dict)):
              raise SchemaError(
                  "requires value {0!r} is neither a string nor an"
                  " object".format(value))
          return value
docs: Additional object or objects required by this object.