docs: def circle(self, cx, cy, r, stroke=None, fill=None, stroke_width=1):
          """
          :param cx: Center X
          :param cy: Center Y
          :param r: Radius
          """
          self.put(' <circle cx="')
          self.put(str(cx))
          self.put('" cy="')
          self.put(str(cy))
          self.put('" r="')
          self.put(str(r))
          self.put('" stroke-width="')
          self.put(str(stroke_width))
          self.put('"')
          if fill:
              self.put(' fill="')
              self.put(fill)
              self.put('"')
          if stroke:
              self.put(' stroke="')
              self.put(stroke)
              self.put('"')
          self.put('/>\n')