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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 get_default(self):
 """Return the default VLAN from the set."""

        length = len(self)
        if length == 0:
            return None
        elif length == 1:
            return self[0]
        else:
            return sorted(self, key=attrgetter('id'))[0]