rem: struct hash_entry *bucket;
add: struct hash_entry const *bucket;
context: hash_get_first (const Hash_table *table){  struct hash_entry *bucket;  if (table->n_entries == 0)    return NULL;  for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)    if (bucket->data)      return bucket->data;  assert (0);  return NULL;}