func SimpleVisit(expr Expr, preFn SimpleVisitFn) (Expr, error) {
	v := simpleVisitor{fn: preFn}
	newExpr, _ := WalkExpr(&v, expr)
	if v.err != nil {
		return nil, v.err
	}
	return newExpr, nil
}
// SimpleVisit is a convenience wrapper for visitors that only have VisitPre
// code and don't return any results except an error. The given function is
// called in VisitPre for every node. The visitor stops as soon as an error is
// returned.
SimpleVisit is a convenience wrapper for visitors that only have VisitPre
code and don't return any results except an error. The given function is
called in VisitPre for every node. The visitor stops as soon as an error is
returned.
// SimpleVisit is a convenience wrapper for visitors that only have VisitPre // code and don ' t return any results except an error . The given function is // called in VisitPre for every node . The visitor stops as soon as an error is // returned .
func SimpleVisit(expr Expr, preFn SimpleVisitFn) (Expr, error) {
	v := simpleVisitor{fn: preFn}
	newExpr, _ := WalkExpr(&v, expr)
	if v.err != nil {
		return nil, v.err
	}
	return newExpr, nil
}
func SimpleVisit ( expr Expr , preFn SimpleVisitFn ) ( Expr , error ) { v := simpleVisitor { fn : preFn } newExpr , _ := WalkExpr ( & v , expr ) if v . err != nil { return nil , v . err } return newExpr , nil }
SimpleVisit is a convenience wrapper for visitors that only have VisitPre
code and don't return any results except an error.
SimpleVisit is a convenience wrapper for visitors that only have VisitPre code and don ' t return any results except an error .