title: LESS mixin logic
body: <p>I have created a LESS mixin for margins that accepts multiple numeric values and spits out a css value/property pair with a rem unit of measurement and a px fall-back.</p>
  
  <p><strong>Here is what I need help with:</strong> </p>
  
  <ol>
  <li>I want the mixin to be able to accept a valid string-based property such as "auto" or "inherit"</li>
  <li>I want to be able to only declare the amount of arguments that is nessecary. eg. If i only need a margin-left, then I only want to have to write something like <code>.margin(nope,nope,nope,1);</code>.</li>
  </ol>
  
  <p>Here is what I have so far:</p>
  
  <pre><code>.margin(@sizeValueTop: auto, @sizeValueRight: 0, @sizeValueBottom: 0, @sizeValueLeft: 0) {
    @pxValueTop: (@sizeValueTop * 16);
    @remValueTop: (@sizeValueTop);
    @pxValueRight: (@sizeValueRight * 16);
    @remValueRight: (@sizeValueRight);
    @pxValueBottom: (@sizeValueBottom * 16);
    @remValueBottom: (@sizeValueBottom);
    @pxValueLeft: (@sizeValueLeft * 16);
    @remValueLeft: (@sizeValueLeft);
    margin-top: ~"@{pxValueTop}px"; 
    margin-top: ~"@{remValueTop}rem";
    margin-right: ~"@{pxValueRight}px"; 
    margin-right: ~"@{remValueRight}rem";
    margin-bottom: ~"@{pxValueBottom}px"; 
    margin-bottom: ~"@{remValueBottom}rem";
    margin-left: ~"@{pxValueLeft}px"; 
    margin-left: ~"@{remValueLeft}rem";
  }
  
  body{
    .margin(1,1,1,1);
  }
  </code></pre>
  
  <p>Any help would be great.</p>