`bisect`

bisect maintains a list in sorted order without sorting after each insertion. Built on binary search.

Source-of-record: Lib/bisect.py, Modules/_bisectmodule.c, bisect docs.

Locate

Function	Returns
`bisect_left(a, x, lo=0, hi=len(a), *, key=None)`	Index where `x` could be inserted to keep sorted; ties go to the left.
`bisect_right(a, x, lo=0, hi=len(a), *, key=None)`	Same; ties go to the right.
`bisect(...)`	Alias for `bisect_right`.

Function	Effect
`insort_left(a, x, lo=0, hi=len(a), *, key=None)`	Insert `x` keeping sorted; ties left.
`insort_right(a, x, lo=0, hi=len(a), *, key=None)`	Insert keeping sorted; ties right.
`insort(...)`	Alias for `insort_right`.

The key argument applies a one-arg key function similar to sorted(..., key=). The list must already be sorted by that key.

bisect doesn't ship find/contains; the recipe is:

i = bisect_left(a, x)
hit = i != len(a) and a[i] == x