Stylus 'gradient()' mixin

gradient-mixin.styl

// Adds a linear gradient with the background coral fallback. The
// last parameter is optional
//
// background: gradient(top, #FFFFFF, #000000, 50%);
//
gradient() {
  if current-property {
    // the fallback for IE
    add-property(current-property[0], mix(arguments[1], arguments[2], arguments[3]?arguments[3]:50%));
    linear-gradient(arguments[0], arguments[1], arguments[2]);
  } else {
    error('gradient() must be used within a property');
  }
}