pub fn py_float_repr(x: f64) -> StringExpand description
CPython repr(float): shortest round-trip decimal digits (David Gay
dtoa mode-0 semantics: among round-tripping candidates prefer the one
nearest the exact binary value, ties to even), fixed notation when the
decimal point position is in (-4, 16], otherwise exponent form with
lowercase e, mandatory sign, and a minimum two-digit exponent.
Integral in-range floats keep a .0 suffix. inf / -inf / nan.
NOTE: Rust’s own {}/{:e} shortest formatter is NOT equivalent — it
diverges from CPython on exact-tie mantissas (e.g. the double nearest
-101065508335255.125 reprs as ...12 in CPython, ...13 via {:e}),
hence the exact-decimal search below.