Traceback (most recent call last):
File "c:\vnstudio\lib\site-packages\vnpy\trader\ui\mainwindow.py", line 281, in open_widget
widget = widget_class(self.main_engine, self.event_engine)
File "c:\vnstudio\lib\site-packages\vnpy\app\cta_backtester\ui\widget.py", line 52, in init
self.init_strategy_settings()
File "c:\vnstudio\lib\site-packages\vnpy\app\cta_backtester\ui\widget.py", line 60, in init_strategy_settings
setting = self.backtester_engine.get_default_setting(class_name)
File "c:\vnstudio\lib\site-packages\vnpy\app\cta_backtester\engine.py", line 246, in get_default_setting
return strategy_class.get_class_parameters()
File "c:\vnstudio\lib\site-packages\vnpy\app\cta_strategy\template.py", line 60, in get_class_parameters
class_parameters[name] = getattr(cls, name)
AttributeError: type object 'DemoStrategy' has no attribute 'fast_windowslow_window'