code: @Deprecated
  	public void addFirstInput(Operator<IN1>... input) {
  		this.input1 = Operator.createUnionCascade(this.input1, input);
  	}
docs: Add to the first input the union of the given operators.
  
  @param input The operator(s) to be unioned with the first input.
  @deprecated This method will be removed in future versions. Use the {@link Union} operator instead.