1  typedef union tree_node *tree;
       2  union tree_node {
       3      tree * use;
       4      VEC_constructor_elt_gc *elts;
       5  };
       6  
       1  typedef union tree_node *tree;
       2  union tree_node {
       3      tree * use;
       4      VEC_constructor_elt_gc *elts;
       5  };
       6