rem: *ht = hash_initialize (HT_UNREMOVABLE_INITIAL_CAPACITY, NULL, hash_pjw, hash_compare_strings, hash_freer); if (*ht == NULL) xalloc_die ();
add: { *ht = hash_initialize (HT_UNREMOVABLE_INITIAL_CAPACITY, NULL, hash_pjw, hash_compare_strings, hash_freer); if (*ht == NULL) xalloc_die (); }
context: AD_mark_helper (Hash_table **ht, char const *filename){  if (*ht == NULL)    *ht = hash_initialize (HT_UNREMOVABLE_INITIAL_CAPACITY, NULL, hash_pjw,			   hash_compare_strings, hash_freer);  if (*ht == NULL)    xalloc_die ();  if (! hash_insert (*ht, filename))    xalloc_die ();}