Process dividends for the next session.

        This will earn us any dividends whose ex-date is the next session as
        well as paying out any dividends whose pay-date is the next session

def process_dividends(self, next_session, asset_finder, adjustment_reader):
        """Process dividends for the next session.

        This will earn us any dividends whose ex-date is the next session as
        well as paying out any dividends whose pay-date is the next session
        """
        position_tracker = self.position_tracker

        # Earn dividends whose ex_date is the next trading day. We need to
        # check if we own any of these stocks so we know to pay them out when
        # the pay date comes.
        held_sids = set(position_tracker.positions)
        if held_sids:
            cash_dividends = adjustment_reader.get_dividends_with_ex_date(
                held_sids,
                next_session,
                asset_finder
            )
            stock_dividends = (
                adjustment_reader.get_stock_dividends_with_ex_date(
                    held_sids,
                    next_session,
                    asset_finder
                )
            )

            # Earning a dividend just marks that we need to get paid out on
            # the dividend's pay-date. This does not affect our cash yet.
            position_tracker.earn_dividends(
                cash_dividends,
                stock_dividends,
            )

        # Pay out the dividends whose pay-date is the next session. This does
        # affect out cash.
        self._cash_flow(
            position_tracker.pay_dividends(
                next_session,
            ),
        )