// 		goto Error
	// 	}
	// 	if e.Op == token.ARROW {
	// 		x.expr = e
	// 		return statement // receive operations may appear in statement context
	// 	}

	// case *syntax.BinaryExpr:
	// 	check.binary(x, e, e.X, e.Y, e.Op)
	// 	if x.mode == invalid {
	// 		goto Error
	// 	}

	case *syntax.Operation:
		if e.Y == nil {
			// unary expression
			if e.Op == syntax.Mul {

pkg go/ast, type BasicLit struct, Value string
pkg go/ast, type BasicLit struct, ValuePos token.Pos
pkg go/ast, type BinaryExpr struct
pkg go/ast, type BinaryExpr struct, Op token.Token
pkg go/ast, type BinaryExpr struct, OpPos token.Pos
pkg go/ast, type BinaryExpr struct, X Expr
pkg go/ast, type BinaryExpr struct, Y Expr
pkg go/ast, type BlockStmt struct
pkg go/ast, type BlockStmt struct, Lbrace token.Pos