@classmethod<EOL><INDENT>def CreatePrecisionHelper(cls, precision):<DEDENT>
precision_helper_class = cls._PRECISION_CLASSES.get(precision, None)<EOL>if not precision_helper_class:<EOL><INDENT>raise ValueError('<STR_LIT>'.format(precision))<EOL><DEDENT>return precision_helper_class<EOL>
Creates a precision helper.

        Args:
          precision (str): precision of the date and time value, which should
              be one of the PRECISION_VALUES in definitions.

        Returns:
          class: date time precision helper class.

        Raises:
          ValueError: if the precision value is unsupported.