<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def adjust(self, amount, update=True, flow=True, fee=0.0):
 """ Adjust capital - used to inject capital to a Strategy. This injection of capital will have no effect on the children. Args: * amount (float):
 Amount to adjust by. * update (bool):
 Force update? * flow (bool):
 Is this adjustment a flow? A flow will not have an impact on the performance (price index). Example of flows are simply capital injections (say a monthly contribution to a portfolio). This should not be reflected in the returns. A non-flow (flow=False) does impact performance. A good example of this is a commission, or a dividend. """

        # adjust capital
        self._capital += amount
        self._last_fee += fee

        # if flow - increment net_flows - this will not affect
        # performance. Commissions and other fees are not flows since
        # they have a performance impact
        if flow:
            self._net_flows += amount

        if update:
            # indicates that data is now stale and must
            # be updated before access
            self.root.stale = True