code: @Override
  	public void accept(Visitor<Operator<?>> visitor) {
  		boolean descend = visitor.preVisit(this);
  		if (descend) {
  			this.input1.accept(visitor);
  			this.input2.accept(visitor);
  			for (Operator<?> c : this.broadcastInputs.values()) {
  				c.accept(visitor);
  			}
  			visitor.postVisit(this);
  		}
  	}
docs: --------------------------------------------------------------------------------------------