protected K standardFirstKey() {
    Entry<K, V> entry = firstEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();
    }
  }
protected K standardFirstKey() {
    Entry<K, V> entry = firstEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();
    }
  }
protected K standardFirstKey ( ) { Entry < K , V > entry = firstEntry ( ) ; if ( entry == null ) { throw new NoSuchElementException ( ) ; } else { return entry . getKey ( ) ; } }
A sensible definition of {@link #firstKey} in terms of {@code firstEntry}. If you override
{@code firstEntry}, you may wish to override {@code firstKey} to forward to this
implementation.
A sensible definition of {