function meth1(){
  return 1;
}
function meth2(input){
  return 2 + input;
}
function result(arg1, cb){
  var result = typeof(cb) == "function" && cb(arg1)
  return result
}
console.log('a'+result(1,meth1()))
console.log('b'+result(1,meth1))
console.log('C'+result(1,meth2))