title: How do I say "if x == A or B or C" as succinctly as possible?
body: <p>I'm pretty sure ruby has an idiom for that.</p>
  
  <p>I just have too many places in my code where I say</p>
  
  <pre><code>if (x == A) || (x == B) || (x ==C)
    do_something
  else
    do_something_else
  end
  </code></pre>
  
  <p>I know I also could do </p>
  
  <pre><code>case x
  when A, B, C
     do_something
  else
     do_something_else
  end
  </code></pre>
  
  <p>but I prefer using <code>if else</code> if there's a nice idiom to make it more succinct.</p>