Function approx_eq 

pub fn approx_eq(
    left: RuntimeValue,
    right: RuntimeValue,
) -> Result<RuntimeValue, String>

a is approximately b — the TOLERANT numeric comparison (== is IEEE bit-exact). Both operands coerce to f64 (approximation is inherently tolerant, so the lossy view is correct here) and compare with the ONE shared isclose definition (logicaffeine_data::ops::logos_approx_eq).