title: What does "match ref" mean in rust?
body: <pre><code>fn main () {
  
     let x: &amp;Option&lt;_&gt; = &amp;Some(90);
  
      match x {
          // no ref
          &amp;Some(y) =&gt; { 
              print!(&quot;{}&quot;, y);
          },
          &amp;None =&gt; { 
          
          },
      }
      
      match x {
          // ref
          &amp;Some(ref y) =&gt; { 
              print!(&quot;{}&quot;, y);
          },
          &amp;None =&gt; { 
          
          },
      }
      
  }
  </code></pre>
  <p>// What's the difference between the two?</p>