title: what is the use back ticks in scala
body: <p>I found following code in a book</p>
  
  <pre><code>val list = List(5, 4, 3, 2, 1)
  val result = (0 /: list) { (`running total`, `next element`) ⇒
    `running total` - `next element`
  }
  </code></pre>
  
  <p>Are backticks used to create a variable name with spaces?</p>