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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 unique_justseen(iterable, key=None):
 """Yields elements in order, ignoring serial duplicates ['A', 'B', 'C', 'D', 'A', 'B'] ['A', 'B', 'C', 'A', 'D'] """

    return map(next, map(operator.itemgetter(1), groupby(iterable, key)))