bisect.bisect_left()

bisect.bisect_left(a, x[, lo[, hi]]) → index

Return the index where to insert item x in list a, assuming a is sorted.

The return value i is such that all e in a[:i] have e < x, and all e in a[i:] have e >= x. So if x already appears in the list, i points just before the leftmost x already there.

Optional args lo (default 0) and hi (default len(a)) bound the slice of a to be searched.