public void Run(IEnvironment env)
 {
     if (Value == null)
     {
         env.CreateIntermediate(Name, (int)W.Evaluate(env).Number, (int)H.Evaluate(env).Number);
     }
     else
     {
         IQueryValue value = new CanvasValue() {Canvas = Value.Evaluate(env).Canvas};
         env.CreateVariable(Name, value);
     }
 }