ES6 tagged template strings, this helped me grok it a bit better

foo.js

  var a = 5;
  var b = 10;
  var c = 2;

  function tag(strings, ...values) {
    console.log(strings[0].replace('\n', '')); // "Hello "
    console.log(strings[1].replace('\n', '')); // " world "
    console.log(values[0]);  // 15
    console.log(values[1]);  // 50

    return "Bazinga!";
  }

  tag`Hello ${ a + b + c }world ${ a * b }`;
  // ~ tag("Hello", a + b + c)
  // ~ tag("world", a * b)
  tag`Hello ${ a + b + c }
world ${ a * b }`;
  // now here the \n is part of the second call string, not the first
  tag`
Hello ${ a + b + c }
world ${ a * b }`;
  // here both are prefixed with a \n newline
  // now we can begin to see, these are two parameters