random.py 文件源码

def getrandbits(self, k):
        """getrandbits(k) -> x.  Generates an int with k random bits."""
        if k <= 0:
            raise ValueError('number of bits must be greater than zero')
        if k != int(k):
            raise TypeError('number of bits should be an integer')
        numbytes = (k + 7) // 8                       # bits / 8 and rounded up
        x = int.from_bytes(_urandom(numbytes), 'big')
        return x >> (numbytes * 8 - k)                # trim excess bits