63     const item: StackItem<T> = {  constant
76       item.data = data;
79     lookup[key] = item;
83     return item;
87     const item = lookup[key];  constant
89     if (item.status === 'pushing') {
90       item.status = 'settled';
102     return item;
110       const item = lookup[key];  constant
112       if (item) {
113         if (item.status === 'pushing') {
117         item.status = 'popping';
123         item.promise = promise;
126         items.push(item);
141       const item = lookup[key];  constant
143       if (item && (item.status === 'settled' || item.status === 'pushing')) {
151       const item = lookup[key];  constant
153       if (item) {
154         if (item.status === 'pushing') {
158         item.status = 'popping';
164         item.promise = promise;
167         items.push(item);
175     const item = lookup[key];  constant
185     item.status = 'popped';
188     return item;