Section Header
  
  
    + name := AVL_SET[E];
  
Section Inherit
  
  
    + parent_set:Expanded SET[E];
  
  
    + parent_avl_tree:Expanded AVL_TREE[E];
  
Section Public 
  
  
    - add e:E <-
  
  
    - fast_add e:E <-
  
  
    - clear_count <-
  
  
    - reference_at e:E :E <-
  
  
    - item index:INTEGER :E <-
    
Section Public  
  
  
    - create:SELF <-
    
  
    - make <-
    
  
  
 Invariant.
  
  
  [
    -? {lost_nodes != NULL};
    -? {lost_nodes = common_lost_nodes.at generating_type};
  ];