code: def make_range(clusters, extend=0):
      
      eclusters = []
      for cluster in clusters:
          xlist, ylist, scores = zip(*cluster)
          score = _score(cluster)
  
          xchr, xmin = min(xlist)
          xchr, xmax = max(xlist)
          ychr, ymin = min(ylist)
          ychr, ymax = max(ylist)
  
          # allow fuzziness to the boundary
          xmax += extend
          ymax += extend
          # because extend can be negative values, we don't want it to be less than min
          if xmax < xmin:
              xmin, xmax = xmax, xmin
          if ymax < ymin:
              ymin, ymax = ymax, ymin
  
          eclusters.append(((xchr, xmin, xmax),
                            (ychr, ymin, ymax), score))
  
      return eclusters
docs: Convert to interval ends from a list of anchors
      extend modifies the xmax, ymax boundary of the box,
      which can be positive or negative
      very useful when we want to make the range as fuzzy as we specify