code: def gets(self, key, default=None, cas_default=None):
          
          defaults = (default, cas_default)
          return self._fetch_cmd(b'gets', [key], True).get(key, defaults)
docs: The memcached "gets" command for one key, as a convenience.
  
          Args:
            key: str, see class docs for details.
            default: value that will be returned if the key was not found.
            cas_default: same behaviour as default argument.
  
          Returns:
            A tuple of (value, cas)
            or (default, cas_defaults) if the key was not found.