code: def register_encoder(self, lookup: Lookup, encoder: Encoder, label: str=None) -> None:
          
          self._register_coder(self._encoders, lookup, encoder, label=label)
docs: Registers the given ``encoder`` under the given ``lookup``.  A unique
          string label may be optionally provided that can be used to refer to
          the registration by name.  For more information about arguments, refer
          to :any:`register`.