Function decode_algol_located 

pub fn decode_algol_located(
    codec: CodecId,
    source_id: impl Into<String>,
    source: &str,
) -> Result<LocatedExpr>

Decodes Algol source into a LocatedExpr, attaching span and trivia origin so source layout round-trips.

Uses crate::default_pratt_table and a default decode budget; call decode_algol_located_with_budget to supply an explicit budget. Raw number literals are carried as a tagged extension form and lowered to concrete number domains later by the runtime decoder.