code: def _norm(self, value):
          
          if isinstance(value, self.valid_types):
              self._byte_value = value * self._unit_value
              self._bit_value = self._byte_value * 8.0
          else:
              raise ValueError("Initialization value '%s' is of an invalid type: %s. "
                               "Must be one of %s" % (
                                   value,
                                   type(value),
                                   ", ".join(str(x) for x in self.valid_types)))
docs: Normalize the input value into the fundamental unit for this prefix
  type.
  
     :param number value: The input value to be normalized
     :raises ValueError: if the input value is not a type of real number