code: def end_of(self, event_id, import_options=True):
          
          event_id = str(event_id)
          if event_id in DatePickerDictionary.items:
              linked_picker = DatePickerDictionary.items[event_id]
              self.config['linked_to'] = linked_picker.config['id']
              if import_options:
                  backup_moment_format = self.config['options']['format']
                  self.config['options'].update(linked_picker.config['options'])
                  self.config['options'].update(self.options_param)
                  if self.format_param or 'format' in self.options_param:
                      self.config['options']['format'] = backup_moment_format
                  else:
                      self.format = linked_picker.format
              # Setting useCurrent is necessary, see following issue
              # https://github.com/Eonasdan/bootstrap-datetimepicker/issues/1075
              self.config['options']['useCurrent'] = False
              self._link_to(linked_picker)
          else:
              raise KeyError(
                  'start-date not specified for event_id "%s"' % event_id)
          return self
docs: Set Date-Picker as the end-date of a date-range.
  
          Args:
              - event_id (string): User-defined unique id for linking two fields
              - import_options (bool): inherit options from start-date input,
                default: TRUE