code: def graft(coll, branch, index):
      '''Graft list branch into coll at index
      '''
      pre = coll[:index]
      post = coll[index:]
      ret = pre + branch + post
      return ref graft(coll, branch, index):
      '''Graft list branch into coll at index
      '''
      pre = coll[:index]
      post = coll[index:]
      ret = pre + branch + post
      return ret
docs: Graft list branch into coll at index