def METHOD_NAME(func):
    """Get the names and default values of a function's arguments.
    A tuple of four things is returned: (args, varargs, varkw, defaults).
    'args' is a list of the argument names (it may contain nested lists).
    'varargs' and 'varkw' are the names of the * and ** arguments or None.
    'defaults' is an n-tuple of the default values of the last n arguments.
    """
    if ismethod(func):
        func = func.__func__
    if not isfunction(func):
        raise TypeError('arg is not a Python function')
    args, varargs, varkw = getargs(func.__code__)
    return args, varargs, varkw, func.__defaults__