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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 and_join(strings):
 """Join the given ``strings`` by commas with last `' and '` conjuction. 'Korea, Japan, China, and Taiwan' :param strings: a list of words to join :type string: :class:`collections.abc.Sequence` :returns: a joined string :rtype: :class:`str`, :class:`basestring` """

    last = len(strings) - 1
    if last == 0:
        return strings[0]
    elif last < 0:
        return ''
    iterator = enumerate(strings)
    return ', '.join('and ' + s if i == last else s for i, s in iterator)