def METHOD_NAME(self, metadata):
    """Method to set the metadata of the multigraph.
    Arguments:
        metadata -- dictionary      the metadata to set on the multigraph
    """
    if metadata == None:
        self._metadata = None
    else:
        if isinstance(metadata, dict) and self._isJsonSerializable(metadata):
            self._metadata = metadata
        else:
            raise TypeError("metadata in Multigraph object needs to be json serializable")