take diff run on separated words and convert the deltas to character offsets

def translate_diff(origtext,deltas):
  'take diff run on separated words and convert the deltas to character offsets'
  lens=[0]+cumsum(map(len,splitpreserve(origtext))) # [0] at the head for like 'length before'
  return [Delta(lens[a],lens[b],''.join(replace)) for a,b,replace in deltas]