Function get_optional 

pub fn get_optional<T>(
    dict: &Bound<'_, PyDict>,
    key: &str,
) -> PyResult<Option<T>>
where
    T: for<'a, 'py> FromPyObject<'a, 'py>,
    for<'a, 'py> PyErr: From<<T as FromPyObject<'a, 'py>>::Error>,

Helper function to get an optional value from a Python dictionary.

Returns

Returns Some(value) if the key exists and extraction succeeds, None if the key is missing or if the value is Python None, or a PyErr if extraction fails.

Errors

Returns PyErr if value extraction fails (but not if the key is missing or value is None).