code: def _massage_metakeys(dct, prfx):
      
      lowprefix = prfx.lower()
      ret = {}
      for k, v in list(dct.items()):
          if not k.lower().startswith(lowprefix):
              k = "%s%s" % (prfx, k)
          ret[k] = v
      return ret
docs: Returns a copy of the supplied dictionary, prefixing any keys that do
      not begin with the specified prefix accordingly.