static IEnumerable<R> Zip<T1, T2, R>((IEnumerable<T1> foo, IEnumerable<T2> bar) sequences, Func<(T1 foo, T2 bar), R> resultSelector)
{
    using (IEnumerator<T1> it1 = sequences.foo.GetEnumerator())
    using (IEnumerator<T2> it2 = sequences.bar.GetEnumerator())
    {
        while (it1.MoveNext() && it2.MoveNext())
            yield return resultSelector((it1.Current, it2.Current));
    }
}

static IEnumerable<R> Zip<T1, T2, R>((IEnumerable<T1>, IEnumerable<T2>) sequences, Func<(T1, T2), R> resultSelector)
{
    using (IEnumerator<T1> it1 = sequences.Item1.GetEnumerator())
    using (IEnumerator<T2> it2 = sequences.Item2.GetEnumerator())
    {
        while (it1.MoveNext() && it2.MoveNext())
            yield return resultSelector((it1.Current, it2.Current));
    }
}

static void Main()
{
    var t = Id((x: 1, y: 2));
    Console.WriteLine(t.x);
}

static T Id<T>(T t) => t;

public abstract class Base
{
    public abstract (int a, int b) Foo();
    public abstract (int, int) Bar();
}

public class Derived : Base
{
    // Error: Cannot change tuple element names when overriding method
    public override (int c, int d) Foo() => (1, 2);
    // Error: Cannot change tuple element names when overriding method
    public override (int a, int b) Bar() => (1, 2);
}