*args should be a tuple (not a list)

[jakebailey]

Running:

def func(a, b=123, *args, **kwargs):
    print("a", type(a))
    print("b",type(b))
    print("args", type(args))
    print("kwargs", type(kwargs))

x = [1, 2, 3]
y = {"foo": 3.141}

func("foo", *x, **y)

Gives:

a <class 'str'>
b <class 'int'>
args <class 'tuple'>
kwargs <class 'dict'>

We are missing type info on both args and kwargs. The latter is #1238, but we have some places where args is assumed to be list, when it should be tuple. It's always tuple, and does not depend on what happened to be unpacked into it.