'Wrapper around C{os.getrandbits}.'

def _randBits(self, nbytes):

    if (self.getrandbits is not None):
        n = self.getrandbits((nbytes * 8))
        hexBytes = (('%%0%dx' % (nbytes * 2)) % n)
        return _fromhex(hexBytes)
    raise SourceNotAvailable('random.getrandbits    is    not    available')
