Function parse_enum 

pub fn parse_enum<E>(input: &str, param: &str) -> PyResult<E>
where
    E: FromStr<Err = ParseError> + IntoEnumIterator + ToString,

Converts a raw string to the enum E, returning a nicely‑formatted PyValueError if the string does not match any variant.

The helper is aimed at Python‑exposed functions that still accept plain &str parameters internally: call parse_enum instead of writing repetitive str::parse() + error‑formatting logic yourself.

Errors

Returns an error if input does not match any known variant of E.