public static CombineAwaitable <T> CxYield <T> (T value) => ComputationExpression.Yield <T> (value);
 public static TMonad CxRun <T, TMonad> (IMonadExpressionBuilder builder, Func <IMonad <T> > body)
     where TMonad : IMonad <T>
 {
     return(ComputationExpression.Run <T, TMonad> (builder, body));
 }