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

    gt_kwargs = {}
    if ('state' in kwargs):
        s = kwargs.pop('state')
        if isinstance(s, (list, tuple)):
            gt_kwargs['stack'] = s
        else:
            gt_kwargs['stack'] = ('root', s)
    if (_other is this):
        def callback(lexer, match, ctx=None):
            if kwargs:
                kwargs.update(lexer.options)
                lx = lexer.__class__(**kwargs)
            else:
                lx = lexer
            s = match.start()
            for (i, t, v) in lx.get_tokens_unprocessed(match.group(), **gt_kwargs):
                (yield ((i + s), t, v))
            if ctx:
                ctx.pos = match.end()
    else:
        def callback(lexer, match, ctx=None):
            kwargs.update(lexer.options)
            lx = _other(**kwargs)
            s = match.start()
            for (i, t, v) in lx.get_tokens_unprocessed(match.group(), **gt_kwargs):
                (yield ((i + s), t, v))
            if ctx:
                ctx.pos = match.end()
    return callback

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

def using(_other, **kwargs):