code: def generateMask
                  ray = @height / 2
                  generated = []
                  generated << "<mask"
                  generated << "id=\"pill-base\""
                  generated << "x=\"0\" y=\"0\" width=\"#{@width}\" height=\"#{@height}\" style=\"fill: #ffffff\""
                  generated << ">"
                  generated << "<circle cx=\"#{ray}\" cy=\"#{ray}\" r=\"#{ray}\"/>"
                  generated << "<circle cx=\"#{@width - ray}\" cy=\"#{ray}\" r=\"#{ray}\"/>"
                  generated << "<rect"
                  generated << "x=\"#{ray}\" y=\"0\" width=\"#{@width - (2 * ray)}\" height=\"#{@height}\"/>"
                  generated << "</mask>"
                  "<defs>" + generated.join(" ") + "</defs>"
              end
docs: <mask id="pill-base" x="0" y="0" width="60" height="20" style="fill: #ffffff" >
       <circle cx="10" cy="10" r="10"/>
       <circle cx="50" cy="10" r="10"/>
       <rect x="10" cy="0" height="20" width="40"/>
   </mask>