Why start_date and end_date are not optional?

[Kroid]

In TradingSession, start_date & end_date - requires fields. But why? In price_handler they are optional values with None as default.

[JamesKBowler]

Are you looking at this part?

        start = None
        end = None
        if self.start_date is not None:
            start = df.index.searchsorted(self.start_date)
        if self.end_date is not None:
            end = df.index.searchsorted(self.end_date)

[juliettejames]

This has been fixed and is present in the latest version. Start and End dates can be changed in backtest.py

Thanks