code: def scale(self):
          
          # use vertices peak-peak rather than exact extents
          scale = float((self.vertices.ptp(axis=0) ** 2).sum() ** .5)
          return scale
docs: What is a representitive number that reflects the magnitude
          of the world holding the paths, for numerical comparisons.
  
          Returns
          ----------
          scale : float
              Approximate size of the world holding this path