How to use the greenlet.greenlet.throw function in greenlet

def throw(self, *args):
        """Immediately switch into the greenlet and raise an exception in it.

        Should only be called from the HUB, otherwise the current greenlet is left unscheduled forever.
        To raise an exception in a safely manner from any greenlet, use :meth:`kill`.

        If a greenlet was started but never switched to yet, then also
        a) cancel the event that will start it
        b) fire the notifications as if an exception was raised in a greenlet

        """
        try:
            greenlet.throw(self, *args)
        finally:
            if self._exception is _NONE and self.dead:
                # the greenlet was never switched to before and it will never be, _report_error was not called
                # the result was not set and the links weren't notified. let's do it here.
                # checking that self.dead is true is essential, because throw() does not necessarily kill the greenlet
                # (if the exception raised by throw() is caught somewhere inside the greenlet).
                if len(args) == 1:
                    arg = args[0]
                    #if isinstance(arg, type):
                    if type(arg) is type(Exception):
                        args = (arg, arg(), None)
                    else:
                        args = (type(arg), arg, None)
                elif not args:
                    args = (GreenletExit, GreenletExit(), None)
                self._report_error(args)

Should only be called from the HUB, otherwise the current greenlet is left unscheduled forever.
        To raise an exception in a safe manner from any greenlet, use :meth:`kill`.

        If a greenlet was started but never switched to yet, then also
        a) cancel the event that will start it
        b) fire the notifications as if an exception was raised in a greenlet
        """
        self.__cancel_start()

        try:
            if not self.dead:
                # Prevent switching into a greenlet *at all* if we had never
                # started it. Usually this is the same thing that happens by throwing,
                # but if this is done from the hub with nothing else running, prevents a
                # LoopExit.
                greenlet.throw(self, *args)
        finally:
            self.__handle_death_before_start(args)

Should only be called from the HUB, otherwise the current greenlet is left unscheduled forever.
        To raise an exception in a safe manner from any greenlet, use :meth:`kill`.

        If a greenlet was started but never switched to yet, then also
        a) cancel the event that will start it
        b) fire the notifications as if an exception was raised in a greenlet
        """
        self.__cancel_start()

        try:
            if not self.dead:
                # Prevent switching into a greenlet *at all* if we had never
                # started it. Usually this is the same thing that happens by throwing,
                # but if this is done from the hub with nothing else running, prevents a
                # LoopExit.
                greenlet.throw(self, *args)
        finally:
            self.__handle_death_before_start(args)