code: def get_arc(self, x_start, y, y_curve, x_end):
          
          template = "M{x},{y} C{x},{c} {e},{c} {e},{y}"
          if self.compact:
              template = "M{x},{y} {x},{c} {e},{c} {e},{y}"
          return template.format(x=x_start, y=y, c=y_curve, e=x_end)
docs: Render individual arc.
  
          x_start (int): X-coordinate of arrow start point.
          y (int): Y-coordinate of arrow start and end point.
          y_curve (int): Y-corrdinate of Cubic Bézier y_curve point.
          x_end (int): X-coordinate of arrow end point.
          RETURNS (unicode): Definition of the arc path ('d' attribute).