human
Here's a good function header given the following:
I wrote the below code

    assert (len(tokens) == 1)
    assert tokens[0].startswith(u'=')
    node_label = tokens[0][1:]
    def node_label_use_pred(n, m=None, l=None):
        if ((l is None) or (node_label not in l)):
            raise TgrepException(u'node_label    ={0}    not    bound    in    pattern'.format(node_label))
        node = l[node_label]
        return (n is node)
    return node_label_use_pred

What's a good function header?
assistant
#Here's a good function header.

def _tgrep_node_label_pred_use_action(_s, _l, tokens):