%%% parse-tree: 
  Expr -> CastExpr
    2 ALTERNATIVE PARSES for nonterminal CastExpr:
      ---- alternative 1 ----
      CastExpr -> AtomExpr
        AtomExpr -> AtomExpr ( Expr )
          AtomExpr -> ( Expr )
            (
            Expr -> CastExpr
              CastExpr -> AtomExpr
                AtomExpr -> x
                  x
            )
          (
          Expr -> CastExpr
            CastExpr -> AtomExpr
              AtomExpr -> x
                x
          )
      ---- alternative 2 ----
      CastExpr -> ( Type ) CastExpr
        (
        Type -> x
          x
        )
        CastExpr -> AtomExpr
          AtomExpr -> ( Expr )
            (
            Expr -> CastExpr
              CastExpr -> AtomExpr
                AtomExpr -> x
                  x
            )
