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,