JavaScript: I don't understant where that 'value' come from, and what that 'set' is? : The task is: </br>
Modify the code of makeCounter() </br>so that the counter can also decrease and set the number:</br>

function makeCounter() {
     let count = 0;

     function counter() {
       return count++
     }

Here is this 'value'. I understand what it does. But what is it, </br>
and where did it come from. How can I use it in general? </br>


          counter.set = value => count = value;
            counter.decrease = () => count--;
        
             return counter;
           }
    
       let counter = makeCounter();
    
       alert( counter() ); // 0
       alert( counter() ); // 1

// Also here. What kind of 'set' is this? </br>
I've seen one in Map.prototype.set(), but there is no Map here. </br>
   

    counter.set(10); // set the new count
    
       alert( counter() ); // 10
    
       counter.decrease(); // decrease the count by 1
    
       alert( counter() ); // 10 (instead of 11)

source: http://javascript.info/function-object </br>
Thanks a lot for you understanding and your help.
