code: def rtl_langs(self):
          
          def is_rtl(lang):
              """
              Returns True if lang is a RTL language
  
              args:
                  lang (str): The language to be checked
  
              Returns:
                  True if lang is an RTL language.
              """
              # Base RTL langs are Arabic, Farsi, Hebrew, and Urdu
              base_rtl = ['ar', 'fa', 'he', 'ur']
  
              # do this to capture both 'fa' and 'fa_IR'
              return any([lang.startswith(base_code) for base_code in base_rtl])
  
          return sorted(set([lang for lang in self.translated_locales if is_rtl(lang)]))
docs: Returns the set of translated RTL language codes present in self.locales.
          Ignores source locale.