code: def requestSchema(self, nym, name, version, sender):
          
          operation = { TARGET_NYM: nym,
                        TXN_TYPE: GET_SCHEMA,
                        DATA: {NAME : name,
                               VERSION: version}
          }
  
          req = Request(sender, operation=operation)
          return self.prepReq(req)
docs: Used to get a schema from Sovrin
          :param nym: nym that schema is attached to
          :param name: name of schema
          :param version: version of schema
          :return: req object