code: def unicode_value(self, string):
          
          result = 0
          # don't accept strings that contain numbers
          if self.regex_has_numbers.search(string):
              raise AbnumException(error_msg % string)
          else:
              num_str = self.regex_values.sub(lambda x: '%s ' % self.values[x.group()],
                                              string)
              # don't accept strings, that contains letters which haven't been be converted to numbers
              try:
                  result = sum([int(i) for i in num_str.split()])
              except Exception as e:
                  raise AbnumException(error_msg % string)
          return result
docs: String argument must be in unicode format.