code: def _dump(self, value, **kwargs):
          
          value = self.dynamo_dump(value, **kwargs)
          if value is None:
              return value
          return {self.backing_type: value}
docs: Entry point for serializing values.  Most custom types should use :func:`~bloop.types.Type.dynamo_dump`.
  
          This wraps the return value of :func:`~bloop.types.Type.dynamo_dump` in DynamoDB's wire format.
          For example, serializing a string enum to an int:
  
          .. code-block:: python
  
              value = "green"
              # dynamo_dump("green") = 2
              _dump(value) == {"N": 2}
  
          If a complex type calls this function with ``None``, it will forward ``None`` to
          :func:`~bloop.types.Type.dynamo_dump`.  This can happen when dumping eg. a sparse
          :class:`~.bloop.types.Map`, or a missing (not set) value.