def METHOD_NAME(self):
    """Return statistics by node type: number of nodes in the graph,
    number of parameters, number of invocations, number of MAC's.
    Note that number of invocations is already included in number of MAC's """
    types = dict()
    for node_dict in self._nodes_by_name.values():
        typ = node_dict['type']
        if typ not in types:
            types[typ] = {'nodes': 0, 'parms': 0, 'uses': 0, 'macs': 0}
        type_dict = types[typ]
        type_dict['nodes'] += 1
        type_dict['parms'] += node_dict['parms']
        type_dict['uses'] += node_dict['uses']
        type_dict['macs'] += node_dict['macs']
    return types