docs: def xform(self, radix, relation):
          """
          Transform a radix and some information to a str according to
          configurations.
  
          :param Radix radix: the radix
          :param int relation: relation of display value to actual value
          :param units: element of UNITS()
          :returns: a string representing the value
          :rtype: str
  
          :raises BasesValueError: if configuration does not work with value
          """
          right = radix.non_repeating_part
          left = radix.integer_part
          repeating = radix.repeating_part
  
          if repeating == []:
              right = self.STRIP.xform(right, relation)
  
          right_str = self.DIGITS.xform(right, radix.base)
          left_str = self.DIGITS.xform(left, radix.base) or '0'
          repeating_str = self.DIGITS.xform(repeating, radix.base)
  
          number = self.NUMBER.xform(
             left_str,
             right_str,
             repeating_str,
             radix.base,
             radix.sign
          )
  
          decorators = self.DECORATORS.decorators(relation)
  
          result = {
             'approx' : decorators.approx_str,
             'space' : ' ' if decorators.approx_str else '',
             'number' : number
          }
  
          return self._FMT_STR % result