u01: Add messages to destructor

u01/node.cpp

@@ -3,9 +3,11 @@
 #include "node.h"
 
 node::~node() {
+  std::cout << "enter ~node() of \"" << get_name() << "\"" << std::endl;
   for (node *child : children) {
     delete child;
   }
+  std::cout << "leave ~node() of \"" << get_name() << "\"" << std::endl;
 }
 
 std::string node::get_name() const { return name; }