code: public void deleteColumn(Mutator<K> mutator, K key, N columnName) {
      mutator.addDeletion(key, columnFamily, columnName, topSerializer);
      executeIfNotBatched(mutator);
    }
docs: Stage this column deletion into the pending mutator. Calls {@linkplain #executeIfNotBatched(Mutator)}
  @param mutator
  @param key
  @param columnName