title: Negate a numerical variable and add 'px' to it in LessCSS
body: <p>I would like to create a function which does the following:</p>
  <pre class="lang-css prettyprint-override"><code>.sprite-size (@width,@height,@x,@y) {
    width:~'@{width}px';
    height:~'@{height}px';
    background: @sprites no-repeat  -~'@{x}px' -~'@{y}px';
  }
  </code></pre>
  <p>I would like to  pass a positive value, in <code>@x</code> and <code>@y</code> and then negate them in the output. The above LESS function outputs the following for the given example:</p>
  <pre class="lang-css prettyprint-override"><code>//LESS
  .header-language-selection {
    .sprite-size(44,21,312,0);
  }
  
  //Outputs CSS
  .header-language-selection {
    width: 44px;
    height: 21px;
    background: url('/Content/images/sprites.png') no-repeat - 312px - 0px;
  }
  </code></pre>
  <p>As you can see the output result includes a space between the <code>-</code> and the <code>px</code>.  Is there any way where one can remove this and achieve what I want?</p>
  <p>I want the output of that line to be: <code>background: url('/Content/images/sprites.png') no-repeat -312px -0px;</code></p>