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

    class DeprecatedClass(new_class.__class__, ):
        deprecated_class = None
        warned_on_subclass = False
        def __new__(metacls, name, bases, clsdict_):
            cls = super(DeprecatedClass, metacls).__new__(metacls, name, bases, clsdict_)
            if (metacls.deprecated_class is None):
                metacls.deprecated_class = cls
            return cls
        def __init__(cls, name, bases, clsdict_):
            meta = cls.__class__
            old = meta.deprecated_class
            if ((old in bases) and (not (warn_once and meta.warned_on_subclass))):
                meta.warned_on_subclass = True
                msg = subclass_warn_message.format(cls=_clspath(cls), old=_clspath(old, old_class_path), new=_clspath(new_class, new_class_path))
                if warn_once:
                    msg += '    (warning    only    on    first    subclass,    there    may    be    others)'
                warnings.warn(msg, warn_category, stacklevel=2)
            super(DeprecatedClass, cls).__init__(name, bases, clsdict_)
        def __instancecheck__(cls, inst):
            return any((cls.__subclasscheck__(c) for c in {type(inst), inst.__class__}))
        def __subclasscheck__(cls, sub):
            if (cls is not DeprecatedClass.deprecated_class):
                return super(DeprecatedClass, cls).__subclasscheck__(sub)
            if (not inspect.isclass(sub)):
                raise TypeError('issubclass()    arg    1    must    be    a    class')
            mro = getattr(sub, '__mro__', ())
            return any(((c in {cls, new_class}) for c in mro))
        def __call__(cls, *args, **kwargs):
            old = DeprecatedClass.deprecated_class
            if (cls is old):
                msg = instance_warn_message.format(cls=_clspath(cls, old_class_path), new=_clspath(new_class, new_class_path))
                warnings.warn(msg, warn_category, stacklevel=2)
            return super(DeprecatedClass, cls).__call__(*args, **kwargs)
    deprecated_cls = DeprecatedClass(name,...

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

def create_deprecated_class(name, new_class, clsdict=None, warn_category=ScrapyDeprecationWarning, warn_once=True, old_class_path=None, new_class_path=None, subclass_warn_message='{cls}    inherits    from    deprecated    class    {old},    please    inherit    from    {new}.', instance_warn_message='{cls}    is    deprecated,    instantiate    {new}    instead.'):