Method visit_lambda

typechecker/src/checker.rs:565–568

(&mut self, _l: &Lambda)

    }

    fn visit_lambda(&mut self, _l: &Lambda) {
        self.visit_expr(&_l.body);
        // todo: this can share a visit args with functions
    }

    fn visit_if_exp(&mut self, _i: &IfExp) {
        self.visit_expr(&_i.body);