def METHOD_NAME(self, idx: int) -> bool:
    if idx not in self.fibers:
        self.last_error = ERROR_INVALID_PARAMETER
        return False
    fiber = self.fibers[idx]
    if fiber.cb is not None:
        self.ql.log.debug(f'Skipping callback function of fiber {fiber.idx} at {fiber.cb:#010x}')
        # TODO: should figure out how to emulate the fiber callback and still return to complete
        # the free api hook.
        #
        # details: normally the emulation flow is diverted by setting the architectural pc reg to
        # the desired address. however that would only take effect when all hooks for the current
        # address are done. here we want to call a native function and regain control once it is
        # done to complete the 'free' api that was started.
        #
        # one way to do that it to use 'ql.emu_start' and emulate the callback from its entry point
        # till it reaches its return address. that would indeed let us regain control and resume the
        # 'free' api hook we started here, but doing that will cause uc to abandon the current
        # emulation session -- effectively ending it. once the hooks for the current address are done,
        # the program will go idle.
        #
        # if we choose to emulate till 'ql.os.exit_point' instead, the program will continue but the
        # hook we are in will not resume and we will never "return" from it. using 'uc.context_save'
        # and 'uc.context_restore' to maintain the current emulation properties does not seem to help
        # here.
        #
        # we skip the fiber callback for now.
        # <SKIP>
        # self.ql.log.debug(f'Invoking callback function of fiber {fiber.idx} at {fiber.cb:#010x}')
        # self.__invoke_callback(fiber)
        # self.ql.log.debug(f'Callback function of fiber {fiber.idx} returned gracefully')
        # </SKIP>
    del self.fibers[idx]
    return True