multiple implicit conversions using tuple syntax

tree.cs

void Main()
{
	Tree<int> m = (((1, 2), (3, 4)), (5, (6, 7)));
	Console.WriteLine(m.Sum());
}

abstract class Tree<T> : IEnumerable<T>
{	
	class Leaf : Tree<T>
	{
		public Leaf(T value) => Value = value;
		public T Value { get; }
		public override IEnumerator<T> GetEnumerator()
		{
			yield return Value;
		}
	}
	
	class Branch : Tree<T>
	{
		public Branch(Tree<T> left, Tree<T> right)
		{
			Left = left;
			Right = right;
		}
		
		public Tree<T> Left {get;}
		public Tree<T> Right {get;}
		public override IEnumerator<T> GetEnumerator()
			=> Left.Concat(Right).GetEnumerator();
	}
	
	public static implicit operator Tree<T>(T it)
		=> new Leaf(it);

	public static implicit operator Tree<T>((Tree<T> left, Tree<T> right) it)
		=> new Branch(it.left, it.right);
		
	public abstract IEnumerator<T> GetEnumerator();
	IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}