code: def change_format(self):
          
          format, valid = QInputDialog.getText(self, _('Format'),
                                               _("Float formatting"),
                                               QLineEdit.Normal,
                                               self.dataModel.get_format())
          if valid:
              format = str(format)
              try:
                  format % 1.1
              except:
                  msg = _("Format ({}) is incorrect").format(format)
                  QMessageBox.critical(self, _("Error"), msg)
                  return
              if not format.startswith('%'):
                  msg = _("Format ({}) should start with '%'").format(format)
                  QMessageBox.critical(self, _("Error"), msg)
                  return
              self.dataModel.set_format(format)
              self.sig_option_changed.emit('dataframe_format', format)
docs: Ask user for display format for floats and use it.
  
          This function also checks whether the format is valid and emits
          `sig_option_changed`.