code: def get_extents(self, element, ranges, range_type='combined'):
          
          if range_type == 'extents':
              return element.nodes.extents
          xdim, ydim = element.nodes.kdims[:2]
          xpad = .05 if self.label_index is None else 0.25
          x0, x1 = ranges[xdim.name][range_type]
          y0, y1 = ranges[ydim.name][range_type]
          xdiff = (x1-x0)
          ydiff = (y1-y0)
          if self.label_position == 'right':
              x0, x1 = x0-(0.05*xdiff), x1+xpad*xdiff
          else:
              x0, x1 = x0-xpad*xdiff, x1+(0.05*xdiff)
          x0, x1 = max_range([xdim.range, (x0, x1)])
          y0, y1 = max_range([ydim.range, (y0-(0.05*ydiff), y1+(0.05*ydiff))])
          return (x0, y0, x1, y1)
docs: A Chord plot is always drawn on a unit circle.