Function format_tsvector 

pub fn format_tsvector(lexs: &[TsLexeme]) -> String

v7.12.0 — render a tsvector in PG’s external form: 'lex':1,2A 'word':3 (single-quoted lexemes, optional :positions, optional weight letter A/B/C/D per position). Lexemes already arrive sorted + deduped from the engine. Used by the wire layer (OID 3614) and by SELECT-text output.