public <R> FlatMapOperator<T, R> flatMap(FlatMapFunction<T, R> flatMapper) {
		if (flatMapper == null) {
			throw new NullPointerException("FlatMap function must not be null.");
		}
		return new FlatMapOperator<T, R>(this, flatMapper);
	}
public < R > FlatMapOperator < T , R > flatMap ( FlatMapFunction < T , R > flatMapper ) { if ( flatMapper == null ) { throw new NullPointerException ( "FlatMap function must not be null." ) ; } return new FlatMapOperator < T , R > ( this , flatMapper ) ; }
Applies a FlatMap transformation on a {@link DataSet}.<br/>
The transformation calls a {@link FlatMapFunction} for each element of the DataSet.
Each FlatMapFunction call can return any number of elements including none.

@param flatMapper The FlatMapFunction that is called for each element of the DataSet.
@return A FlatMapOperator that represents the transformed DataSet.

@see FlatMapFunction
@see FlatMapOperator
@see DataSet