Creates an ellipse
        @type  cx: string or int
        @param cx:  starting x-coordinate  
        @type  cy: string or int
        @param cy:  starting y-coordinate 
        @type  rx: string or int
        @param rx:  radius in x direction 
        @type  ry: string or int
        @param ry:  radius in y direction
        @type  strokewidth: string or int
        @param strokewidth:  width of the pen used to draw
        @type  stroke: string (either css constants like "black" or numerical values like "#FFFFFF")
        @param stroke:  color with which to draw the outer limits
        @type  fill: string (either css constants like "black" or numerical values like "#FFFFFF")
        @param fill:  color with which to fill the element (default: no filling)
        @return:  an ellipse object

def createEllipse(self, cx, cy, rx, ry, strokewidth=1, stroke='black', fill='none'):
        """
        Creates an ellipse
        @type  cx: string or int
        @param cx:  starting x-coordinate  
        @type  cy: string or int
        @param cy:  starting y-coordinate 
        @type  rx: string or int
        @param rx:  radius in x direction 
        @type  ry: string or int
        @param ry:  radius in y direction
        @type  strokewidth: string or int
        @param strokewidth:  width of the pen used to draw
        @type  stroke: string (either css constants like "black" or numerical values like "#FFFFFF")
        @param stroke:  color with which to draw the outer limits
        @type  fill: string (either css constants like "black" or numerical values like "#FFFFFF")
        @param fill:  color with which to fill the element (default: no filling)
        @return:  an ellipse object
        """
        style_dict = {'fill':fill, 'stroke-width':strokewidth, 'stroke':stroke}
        myStyle = StyleBuilder(style_dict)
        e = Ellipse(cx, cy, rx, ry)
        e.set_style(myStyle.getStyle())
        return e