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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 default_encode(v):
 """convert ObjectId, datetime, date into string """

    if isinstance(v, ObjectId):
        return unicode_type(v)

    if isinstance(v, datetime):
        return format_time(v)

    if isinstance(v, date):
        return format_time(v)

    return v