How to use cascading.tuple.io

public TuplePair readTuplePair( TuplePair tuplePair ) throws IOException
 {
 Tuple[] tuples = TuplePair.tuples( tuplePair );
 readTuple( tuples[ 0 ] ); // guaranteed to not be null
 readTuple( tuples[ 1 ] ); // guaranteed to not be null
 return tuplePair;
 }

public void writeTuplePair( TuplePair tuplePair ) throws IOException
 {
 Tuple[] tuples = TuplePair.tuples( tuplePair );
 write( tuples[ 0 ] );
 write( tuples[ 1 ] );
 }

public TuplePair readTuplePair() throws IOException
 {
 return readTuplePair( new TuplePair() );
 }

@Override
protected Tuple unwrapGrouping( Tuple key )
 {
 return ( (IndexTuple) key ).getTuple();
 }

@Override
protected TuplePair createTuple()
 {
 return new TuplePair();
 }
}

@Override
protected ValueTuple createTuple()
 {
 return new ValueTuple();
 }
}

@Override
protected KeyTuple createTuple()
 {
 return new KeyTuple();
 }
}

@Override
public void close() throws IOException
 {
 tupleInputStream.close();
 }
};

@Override
protected T createTuple()
 {
 return (T) new IndexTuple();
 }

@Override
public void write( TupleOutputStream stream, Object element ) throws IOException
 {
 elementWriter.write( stream, type, element );
 }
};

@Override
public int compareTo( Tuple other )
 {
 if( other instanceof TuplePair )
  return compareTo( (TuplePair) other );
 else
  return -1;
 }

@Override
protected KeyIndexTuple createTuple()
 {
 return new KeyIndexTuple();
 }

public void writeElementArray( Object[] elements ) throws IOException
 {
 writeIntInternal( elements.length );
 for( Object element : elements )
  writeElement( element );
 }

@Override
protected ValueIndexTuple createTuple()
 {
 return new ValueIndexTuple();
 }

/**
 * Method write is used by Hadoop to write this Tuple instance out to a file.
 *
 * @throws java.io.IOException when
 */
private void write( Tuple tuple ) throws IOException
 {
 writeUnTyped( tuple );
 }

@Override
protected TuplePair createTuple()
 {
 return new TuplePair();
 }
}

@Override
protected ValueTuple createTuple()
 {
 return new ValueTuple();
 }
}

@Override
protected KeyTuple createTuple()
 {
 return new KeyTuple();
 }
}

@Override
public int compareTo( Object other )
 {
 if( other instanceof TuplePair )
  return compareTo( (TuplePair) other );
 else
  return -1;
 }

@Override
protected KeyIndexTuple createTuple()
 {
 return new KeyIndexTuple();
 }