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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 getInterval(self):
 """Vocabulary of date intervals to calculate the "To" field date based from the "From" field date. """

        items = (
            ("", _(u"Not set")),
            ("1", _(u"daily")),
            ("7", _(u"weekly")),
            ("30", _(u"monthly")),
            ("90", _(u"quarterly")),
            ("180", _(u"biannually")),
            ("365", _(u"yearly")),
        )
        return DisplayList(items)