code: def get(self, attr: FetchAttribute) -> MaybeBytes:
          
          attr_name = attr.value.decode('ascii')
          method = getattr(self, '_get_' + attr_name.replace('.', '_'))
          return method(attr)
docs: Return the bytes representation of the given message attribue.
  
          Args:
              attr: The fetch attribute.
  
          Raises:
              :class:`NotFetchable`