code: function inset (frame, top, right, bottom, left) {
    var frameCopy = clone(frame);
  
    // inset(myFrame, 10, 0) => inset(myFrame, 10, 0, 10, 0)
    if (typeof bottom === 'undefined') {
      bottom = top;
      left = right;
    }
  
    // inset(myFrame, 10) => inset(myFrame, 10, 10, 10, 10)
    if (typeof right === 'undefined') {
      right = bottom = left = top;
    }
  
    frameCopy.x += left;
    frameCopy.y += top;
    frameCopy.height -= (top + bottom);
    frameCopy.width -= (left + right);
  
    return frameCopy;
  }
docs: Creates a new frame by a applying edge insets. This method accepts CSS
  shorthand notation e.g. inset(myFrame, 10, 0);
  
  @param {Frame} frame
  @param {Number} top
  @param {Number} right
  @param {?Number} bottom
  @param {?Number} left
  @return {Frame}