code: def namedb_flatten_history( hist ):
      
      ret = []
      block_ids = sorted(hist.keys())
      for block_id in block_ids:
          vtxinfos = hist[block_id]
          for vtxinfo in vtxinfos:
              info = copy.deepcopy(vtxinfo)
              ret.append(info)
  
      return ret
docs: Given a name's history, flatten it into a list of deltas.
      They will be in *increasing* order.