Function parse_pnca_resistance_snps 

fn parse_pnca_resistance_snps(
    csv: &str,
) -> (BTreeMap<isize, (u8, BTreeMap<u8, (Vec<String>, String)>)>, BTreeMap<usize, (String, BTreeMap<String, (Vec<String>, String)>)>)

Parses tbprofiler/mutations.csv, keeping only pncA rows whose mutation is a simple nucleotide substitution (c.POS[wt]>[alt], promoter or coding) or a single-codon amino acid substitution / nonsense call (p.WtNNNAlt / p.WtNNN*).

Frameshifts, in-frame indels, delins, and stop-codon extensions (fs, del, dup, delins, ext) are not positioned by this simple gapless-alignment model and are skipped — same limitation as the rest of this codebase, which only calls substitutions, not indels.