Function deserialize_opt_maybe_quoted 

pub fn deserialize_opt_maybe_quoted<'de, T, D>(
    deserializer: D,
) -> Result<Option<T>, D::Error>
where
    T: FromStr + Deserialize<'de>,
    T::Err: Display,
    D: Deserializer<'de>,

Deserializes an optional value that can be represented as either its native type or a quoted string.