docs: def _init_settings(self):
          """ Init setting """
          self._show_whitespaces = False
          self._tab_length = 4
          self._use_spaces_instead_of_tabs = True
          self.setTabStopWidth(self._tab_length *
                               self.fontMetrics().width(" "))
          self._set_whitespaces_flags(self._show_whitespaces)