code: public boolean deleteEntry(int index) {
      System.arraycopy(entries, index + 1, entries, index, numEntries - index - 1);
      entries[--numEntries] = null;
      return true;
    }
docs: Deletes the entry at the specified index and shifts all entries after the
  index to left.
  
  @param index the index at which the entry is to be deleted
  @return true id deletion was successful