code: def _is_string(cls, arg):
          
  
          isAny = arg == CPEComponent2_3_WFN.VALUE_ANY
          isNa = arg == CPEComponent2_3_WFN.VALUE_NA
  
          return not (isAny or isNa)
docs: Return True if arg is a string value,
          and False if arg is a logical value (ANY or NA).
  
          :param string arg: string to check
          :returns: True if value is a string, False if it is a logical value.
          :rtype: boolean
  
          This function is a support function for _compare().