public function round($topLeft, $topRight = null, $bottomRight = null, $bottomLeft = null)
    {
        return $this->addItem('ro', implode(',', func_get_args()));
    }
public function round($topLeft, $topRight = null, $bottomRight = null, $bottomLeft = null)
    {
        return $this->addItem('ro', implode(',', func_get_args()));
    }
public function round ( $ topLeft , $ topRight = null , $ bottomRight = null , $ bottomLeft = null ) { return $ this -> addItem ( 'ro' , implode ( ',' , func_get_args ( ) ) ) ; }
Rounds the corners of the image.

Parameters behave like CSS border radiuses, the number of given
parameters modifies the function behaviour. Either 1 or 4 parameters
are required.

<li>If 1 parameter is given, all corners are rounded with the same
radius.
<li>If 4 parameters are given, corners are rounded with their respective
radiuses.

@param type $topLeft     General radius or radius on the top left corner
@param type $topRight    Radius on the top right corner
@param type $bottomRight Radius on the bottom right corner
@param type $bottomLeft  Radius on the bottom left corner

@return \self
Rounds the corners of the image .