code: def add_localedir_translations(self, localedir):
          
          global _localedirs
          if localedir in self.localedirs:
              return
          self.localedirs.append(localedir)
          full_localedir = os.path.join(localedir, 'locale')
          if os.path.exists(full_localedir):
              translation = self._new_gnu_trans(full_localedir)
              self.merge(translation)
docs: Merge translations from localedir.