This is makeindex, version 2.15 [TeX Live 2019/dev] (kpathsea + Thai support).
Scanning style file ./python.ist.......done (7 attributes redefined, 0 ignored).
Scanning input file flex_extract.idx....done (30 entries accepted, 0 rejected).
Sorting entries....done (141 comparisons).
Generating output file flex_extract.ind....done (73 lines written, 0 warnings).
Output written in flex_extract.ind.
Transcript written in flex_extract.ilg.