code: def map(self, data):
          
          result = []
          for char in data:
              ret = None
              for lookup in self.mapping:
                  ret = lookup(char)
                  if ret is not None:
                      break
              if ret is not None:
                  result.append(ret)
              else:
                  result.append(char)
          return result
docs: Mapping part of string preparation.