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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 active_days(records):
 """ The number of days during which the user was active. A user is considered active if he sends a text, receives a text, initiates a call, receives a call, or has a mobility point. """

    days = set(r.datetime.date() for r in records)
    return len(days)