code: def diff_encode(line, transform):
      
      coords = [transform(x, y) for (x, y) in line.coords]
  
      pairs = zip(coords[:], coords[1:])
      diffs = [(x2 - x1, y2 - y1) for ((x1, y1), (x2, y2)) in pairs]
  
      return coords[:1] + [(x, y) for (x, y) in diffs if (x, y) != (0, 0)]
docs: Differentially encode a shapely linestring or ring.