Function gluon_base::merge::merge_fn

pub fn merge_fn<'a, 'b, F, G, H, A: ?Sized, B: ?Sized, A1, B1, R>(
    a_original: &'a A,
    g: G,
    a: Option<A1>,
    b_original: &'b B,
    h: H,
    b: Option<B1>,
    merger: F
) -> Option<R>
where
    F: FnOnce(A1, B1) -> R,
    G: FnOnce(&'a A) -> A1,
    H: FnOnce(&'b B) -> B1,