For each element X i in X, calculate the cumulative sum of X i in the
backward direction, i.e., (X i + X i-1 + X i-2 …), until the value is no smaller than Y.
If the cumulative sum never exceeds Y, return 0.
Parameters:
X (Constant) – A vector/tuple/matrix/table whose elements must be non-negative numbers.
threshold (Constant) – A scalar indicating the threshold.
