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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 _invariant(self, rank, n):
 """Computes the delta value for the sample."""

        minimum = n + 1

        for i in self._invariants:
            delta = i._delta(rank, n)
            if delta < minimum:
                minimum = delta

        return math.floor(minimum)