Return all tags found in the value stream.

    Returns:
      A `{tagType: ['list', 'of', 'tags']}` dictionary.

def Tags(self):
    """Return all tags found in the value stream.

    Returns:
      A `{tagType: ['list', 'of', 'tags']}` dictionary.
    """
    return {
        TENSORS: list(self.tensors_by_tag.keys()),
        # Use a heuristic: if the metagraph is available, but
        # graph is not, then we assume the metagraph contains the graph.
        GRAPH: self._graph is not None,
        META_GRAPH: self._meta_graph is not None,
        RUN_METADATA: list(self._tagged_metadata.keys())
    }