This is makeindex, version 2.15 [TeX Live 2021] (kpathsea + Thai support).
Scanning style file ./python.ist.......done (7 attributes redefined, 0 ignored).
Scanning input file nest.idx....done (168 entries accepted, 0 rejected).
Sorting entries....done (1353 comparisons).
Generating output file nest.ind....done (314 lines written, 0 warnings).
Output written in nest.ind.
Transcript written in nest.ilg.