function sayFullName(first, last) {
  console.log('hi ' + first + ' ' + last);
}

function sayHi() {
  console.log('hi');
}

function sayHiTo(name) {
  console.log('hi ' + name);
}

function runWithDebugger(callback, optionalArray) {
  debugger;
  if (arguments.length > 1 && Array.isArray(optionalArray)) {
    callback.apply(this,optionalArray);
  } else if (arguments.length > 1 && !Array.isArray(optionalArray)) {
    console.log('The second argument must be an array.')
  } else {
    console.log(arguments.length);
    callback();
  }
}

runWithDebugger(sayFullName, ['Roland','Deschain']);