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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ipv4_prefix_to_mask(prefix):
 """ ipv4 cidr prefix to net mask :param prefix: cidr prefix , rang in (0, 32) :type prefix: int :return: dot separated ipv4 net mask code, eg: 255.255.255.0 :rtype: str """

    if prefix > 32 or prefix < 0:
        raise ValueError("invalid cidr prefix for ipv4")
    else:
        mask = ((1 << 32) - 1) ^ ((1 << (32 - prefix)) - 1)
        eight_ones = 255  # 0b11111111
        mask_str = ''
        for i in range(0, 4):
            mask_str = str(mask & eight_ones) + mask_str
            mask = mask >> 8
            if i != 3:
                mask_str = '.' + mask_str
        return mask_str