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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 period(argument):
 """ Detect desired time period for the argument """

        since, until, period = None, None, None
        if "today" in argument:
            since = Date("today")
            until = Date("today")
            until.date += delta(days=1)
            period = "today"
        elif "yesterday" in argument:
            since = Date("yesterday")
            until = Date("yesterday")
            until.date += delta(days=1)
            period = "yesterday"
        elif "year" in argument:
            if "last" in argument:
                since, until = Date.last_year()
                period = "the last fiscal year"
            else:
                since, until = Date.this_year()
                period = "this fiscal year"
        elif "quarter" in argument:
            if "last" in argument:
                since, until = Date.last_quarter()
                period = "the last quarter"
            else:
                since, until = Date.this_quarter()
                period = "this quarter"
        elif "month" in argument:
            if "last" in argument:
                since, until = Date.last_month()
            else:
                since, until = Date.this_month()
            period = since.datetime.strftime("%B")
        else:
            if "last" in argument:
                since, until = Date.last_week()
            else:
                since, until = Date.this_week()
            period = "the week {0}".format(since.datetime.strftime("%V"))
        return since, until, period