rem: struct item *k = xmalloc (sizeof (struct item));
add: struct item *k = xmalloc (sizeof *k);
context: new_item (const char *str){  struct item *k = xmalloc (sizeof (struct item));  k->str = (str ? xstrdup (str): NULL);  k->left = k->right = NULL;  k->balance = 0;  /* T1. Initialize (COUNT[k] <- 0 and TOP[k] <- ^).  */  k->count = 0;  k->qlink = NULL;  k->top = NULL;  return k;}