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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 rank(self, value):
 """Returns the rank and count of the value in the btree."""

        i = 0
        n = len(self._tree)
        rank = 0
        count = 0
        while i < n:
            cur = self._tree[i]
            if value < cur:
                i = 2 * i + 1
                continue
            elif value > cur:
                rank += self._counts[i]
                # subtract off the right tree if exists
                nexti = 2 * i + 2
                if nexti < n:
                    rank -= self._counts[nexti]
                    i = nexti
                    continue
                else:
                    return (rank, count)
            else:  # value == cur
                count = self._counts[i]
                lefti = 2 * i + 1
                if lefti < n:
                    nleft = self._counts[lefti]
                    count -= nleft
                    rank += nleft
                    righti = lefti + 1
                    if righti < n:
                        count -= self._counts[righti]
                return (rank, count)
        return (rank, count)