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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 now(timezone=None):
 """ Return a naive datetime object for the given ``timezone``. A ``timezone`` is any pytz- like or datetime.tzinfo-like timezone object. If no timezone is given, then UTC is assumed. This method is best used with pytz installed:: pip install pytz """

    d = datetime.datetime.utcnow()
    if not timezone:
        return d

    return to_timezone(d, timezone).replace(tzinfo=None)