*在python中是什么意思

Question

嗨，我想阅读python文档，我看到了很多，我知道*函数参数表示函数获取列表，**表示函数获取字典，但是我无法理解其他函数..
抱歉，我很困惑

x2, y2 = zip(*zip(x, y)) (i cant understand * in this state means what )

def parrot(voltage, state='a stiff', action='voom'):
    print("-- This parrot wouldn't", action, end=' ')
    print("if you put", voltage, "volts through it.", end=' ')
    print("E's", state, "!")
d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}
parrot(**d) ( and why we use ** before d .. d is dictionary )