Function or variable, literally do not care.

wat.js

// Is this a thing that people do? If so, what is it called? If not, why is it a bad idea? Answers on a tweet please. @hughrawlinson

var π = function(f,obj){
  try{
    f(obj());
  }
  catch(e){
    f(obj);
  }
};

var a = 1;

var b = function(){return 1};

π(function(arg){
    console.log("Number: "+(arg+1));
},a);

π(function(arg){
    console.log("Function: "+(arg+1));
},b);

// This function doesn't care if you've given it a value, or a function that returns a value
var updateBackgroundColor = function(color){
    π(function(c){
        // or however you update the background color
        document.body.background.color = c;
    },color);
}

// This works
var col = '#ffffff';
updateBackgroundColor(col);

// But so does this
updateBackgroundColor(goGetAColorFromSomeWeirdGenerativeProcessOrGetRequestOrSomewhereElseAndReturnItHere);
// where
goGetAColorFromSomeWeirdGenerativeProcessOrGetRequestOrSomewhereElseAndReturnItHere();
// is a function that returns a color