'Execute tool.handle_input with incoming specified by kwds
(optionally extending a previous state).'

def __handle_with_incoming(self, previous_state=None, **kwds):

    if previous_state:
        incoming = self.__to_incoming(previous_state, **kwds)
    else:
        incoming = kwds
    return self.tool.handle_input(trans=self.trans, incoming=incoming)
