class JoinedStreams {

	public <KEY> Where<KEY> where(KeySelector<T1, KEY> keySelector)  {
		requireNonNull(keySelector);
		final TypeInformation<KEY> keyType = TypeExtractor.getKeySelectorTypes(keySelector, input1.getType());
		return where(keySelector, keyType);
	}

	public  JoinedStreams(DataStream<T1> input1, DataStream<T2> input2);

}