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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 dropna(self):
 """Returns MultiIndex without any rows containing null values according to Baloo's convention. Returns ------- MultiIndex MultiIndex with no null values. """

        not_nas = [v.notna() for v in self.values]
        and_filter = reduce(lambda x, y: x & y, not_nas)

        return self[and_filter]