Function serialize_usize_or_max 

pub(crate) fn serialize_usize_or_max<S>(
    value: &usize,
    serializer: S,
) -> Result<S::Ok, S::Error>
where
    S: Serializer,

Serialize a usize as "max" if it equals usize::MAX, as a string if it exceeds i64::MAX (TOML integer limit), or as a plain number otherwise.