How to use cascading.flow.stream.element

@Override
public Throwable call() throws Exception
 {
 return map( null );
 }

/**
 * This allows the tuple to honor the hasher and comparators, if any
 *
 * @param object the tuple to wrap
 * @return a DelegatedTuple instance
 */
protected final Tuple getDelegatedTuple( Tuple object )
 {
 if( groupHasher == null )
  return object;
 return new DelegatedTuple( object );
 }

@Override
public boolean equals( Object object )
 {
 return compareTo( object ) == 0;
 }

@Override
public void start( Duct previous )
 {
 if( next != null )
  super.start( previous );
 }

@Override
public void complete( Duct previous ) {
  if( next != null ) {
    super.complete(previous);
  }
}

@Override
public void initialize()
 {
 super.initialize();
 initComparators();
 keys = createKeySet();
 count.set( numIncomingEventingPaths ); // the number of paths incoming
 }

@Override
public void prepare()
 {
 super.prepare();
 keyValues = createKeyValuesArray();
 closure = new MemoryCoGroupClosure( flowProcess, splice.getNumSelfJoins(), keyFields, valuesFields );
 if( grouping != null && splice.getJoinDeclaredFields() != null && splice.getJoinDeclaredFields().isNone() )
  grouping.joinerClosure = closure;
 }

@Override
public void complete( Duct previous )
 {
 if( next != null )
  super.complete( previous );
 }

@Override
public void start( Duct previous )
 {
 if( next != null )
  super.start( previous );
 }

@Override
public void start( Duct previous )
 {
 if( next != null )
  super.start( previous );
 }

@Override
public void complete( Duct previous )
 {
 if( next != null )
  super.complete( previous );
 }

@Override
public void initialize()
 {
 super.initialize();
 groupAssertion = every.getGroupAssertion();
 reducing = (Reducing) getNext();
 }

@Override
public synchronized void start( Duct previous )
 {
 if( started )
  return;
 super.start( previous );
 started = true;
 }

protected void handleReThrowableException( String message, Throwable throwable )
 {
 trapHandler.handleReThrowableException( message, throwable );
 }

protected void handleException( Throwable exception, TupleEntry tupleEntry )
 {
 handleException( trapName, trap, exception, tupleEntry );
 }

@Override
public void start( Duct previous )
 {
 if( next != null )
  super.start( previous );
 }

@Override
public void complete( Duct previous )
 {
 if( next != null )
  super.complete( previous );
 }

@Override
public void complete( Duct previous )
 {
 if( next != null )
  super.complete( previous );
 }

@Override
public void run( Object input ) throws Throwable
 {
 Throwable throwable = map( input );
 if( throwable != null )
  throw throwable;
 }

@Override
public void start( Duct previous )
{
  if( next != null ) {
    super.start(previous);
  }
}