public FunApp(ElmAstNode rator, params ElmAstNode[] rands)
 {
     Rator = rator;
     Rands.AddRange(rands);
 }
 public FunApp(ElmAstNode rator)
 {
     Rator = rator;
 }
 public CaseExp(ElmAstNode exp)
 {
     Exp = exp;
 }