pub trait VisitMut<T> {
// Provided methods
fn visit_mut_expr(&mut self, expr: &mut Expr<T>) { ... }
fn visit_mut_any(&mut self, Any: &mut Any<T>) { ... }
fn visit_mut_all(&mut self, All: &mut All<T>) { ... }
fn visit_mut_not(&mut self, Not: &mut Not<T>) { ... }
fn visit_mut_var(&mut self, _var: &mut Var<T>) { ... }
fn visit_mut_const(&mut self, _b: &mut bool) { ... }
}