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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 report_collection_diff(from_collection, to_collection, from_id, to_id):
 """Report the collected test difference between two nodes. :returns: detailed message describing the difference between the given collections, or None if they are equal. """

    if from_collection == to_collection:
        return None

    diff = unified_diff(from_collection, to_collection, fromfile=from_id, tofile=to_id)
    error_message = (
        u"Different tests were collected between {from_id} and {to_id}. "
        u"The difference is:\n"
        u"{diff}"
    ).format(from_id=from_id, to_id=to_id, diff="\n".join(diff))
    msg = "\n".join([x.rstrip() for x in error_message.split("\n")])
    return msg