Function default_extend_tuple_d

fn default_extend_tuple_d<D, C, B, A, ED, EC, EB, EA>(
    iter: impl Iterator<Item = (D, C, B, A)>,
    d: &mut ED,
    c: &mut EC,
    b: &mut EB,
    a: &mut EA,
)
where
    ED: Extend<D>,
    EC: Extend<C>,
    EB: Extend<B>,
    EA: Extend<A>,