/// <summary>
/// Return a reference to this <see cref="BehaviorSink{T}" /> as a <see cref="Behavior{T}" />.
/// </summary>
/// <typeparam name="T">The type of the behavior sink.</typeparam>
/// <param name="b">The behavior sink.</param>
/// <returns>A reference to this <see cref="BehaviorSink{T}" /> as a <see cref="Behavior{T}" />.</returns>
public static Behavior <T> AsBehavior <T>(this BehaviorSink <T> b) => b;
public static void Send <T>(this BehaviorSink <T> b, T a) => b.SendImpl(a);