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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 bymonthday(self):
 """ The month days where the recurrence will be applied. """

        retval = []
        if self.rule._bymonthday:
            retval += self.rule._bymonthday
        if self.rule._bynmonthday:
            retval += self.rule._bynmonthday
        return retval