how to return opposite of true or false : I was interview in company and i was asked a question , question was bti strange so wanted to ask with expert guys.

The question suppose i have function which returns bool type, Lets say this :


    public bool func(int param)
    {
      bool retVal;
      
     //here is some algorithm which as a result either set the retVal to false or true, It doesnt matter what is algo, the only thing important is it either do retVal=false or retVal=true
            
     // The question is i have to write the algo here which in case if the previous algo gives us  retVal=fale then it should return true and if retVal=true then return flase      
      
    }

**What should be that algo ?*