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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 coerce_to_list(items, preprocess=None):
 """Given an instance or list, coerce to list. With optional preprocessing. """

    if not isinstance(items, list):
        items = [items]
    if preprocess:
        items = list(map(preprocess, items))
    return items