human
I wrote the below code

    def decorator(model_cls, registration_name=None):
        'Registers    &    returns    model_cls    with    registration_name    or    default    name.'
        model_name = (registration_name or _default_name(model_cls))
        if (model_name in _MODELS):
            raise ValueError(('Model    %s    already    registered.' % model_name))
        _MODELS[model_name] = model_cls
        return model_cls
    if callable(name):
        model_cls = name
        return decorator(model_cls, registration_name=_default_name(model_cls))
    return (lambda model_cls: decorator(model_cls, name))

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

def register_model(name=None):