title: How do I do transparent vendor mixins in Stylus when the mixin function is an argument?
body: <p>Making a mixin for properties like <code>border-radius</code> is easy:</p>
  
  <pre><code>vendor(name, args)
      -webkit-{name} args
      -moz-{name} args
      -ie-{name} args
      -o-{name} args
      {name} args
  
  border-radius()
      vendor('border-radius', arguments)
  
  #test
      border-radius 5px
  </code></pre>
  
  <p>But what if I want to create a transparent vendor mixin for <code>linear-gradient</code>? Unlike <code>border-radius</code>, <code>linear-gradient</code> is not a property but an argument, e.g.</p>
  
  <pre><code>#test
      background-image linear-gradient(top, #f00 0%, #00f 100%)
  </code></pre>
  
  <p>I'm thinking I have to create a mixin called <code>background-image</code> and check if the first argument is <code>linear-gradient</code>. Is Stylus capable of such advanced logic? If so, how can I accomplish what I'm trying to do?</p>
  
  <p>Thanks for any help on the matter.</p>