title: In coffeescript, what's the difference between "is not" and "!="?
body: <p>I've got this line of code:</p>
  
  <pre><code>console.log "source = #{@source.alignment} unit = #{unit.alignment}: " + (@source.alignment is not unit.alignment)
  </code></pre>
  
  <p>This is printing this out to the console:</p>
  
  <blockquote>
    <p>source = good unit = bad: <strong>false</strong></p>
  </blockquote>
  
  <p>Why is it printing "false"?  Shouldn't it be printing "true"?  Logically, good "is not" bad.</p>
  
  <p>This</p>
  
  <pre><code>console.log "source = #{@source.alignment} unit = #{unit.alignment}: " + (@source.alignment != unit.alignment)
  </code></pre>
  
  <p>prints </p>
  
  <blockquote>
    <p>source = good unit = bad: <strong>true</strong></p>
  </blockquote>
  
  <p>as expected.  </p>
  
  <p>What's the difference?  When should I use <code>is not</code>?</p>