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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 get_common_xs(entries):
 """Return a mask of where there are Xs in all routing table entries. For example ``01XX`` and ``XX1X`` have common Xs in the LSB only, for this input this method would return ``0b0001``:: 0b0001 """

    # Determine where there are never 1s in the key and mask
    key = 0x00000000
    mask = 0x00000000

    for entry in entries:
        key |= entry.key
        mask |= entry.mask

    # Where there are never 1s in the key or the mask there are Xs which are
    # common to all entries.
    return (~(key | mask)) & 0xffffffff