code: @Override
      public <G, H> Choice6<A, B, C, D, G, H> biMap(Function<? super E, ? extends G> lFn,
                                                    Function<? super F, ? extends H> rFn) {
          return match(Choice6::a, Choice6::b, Choice6::c, Choice6::d, e -> e(lFn.apply(e)), f -> f(rFn.apply(f)));
      }
docs: {@inheritDoc}