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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def drop_tip(self, location=None, home_after=True):
 """ Drop the pipette's current tip Notes ----- If no location is passed, the pipette defaults to its `trash_container` (see :any:`Pipette`) Parameters location : :any:`Placeable` or tuple(:any:`Placeable`, :any:`Vector`) The :any:`Placeable` (:any:`Well`) to perform the drop_tip. Can also be a tuple with first item :any:`Placeable`, second item relative :any:`Vector` Returns ------- This instance of :class:`Pipette`. Examples -------- .. # drops the tip in the fixed trash # drops the tip back at its tip rack """

        if not self.tip_attached:
            log.warning("Cannot drop tip without a tip attached.")

        if not location and self.trash_container:
            location = self.trash_container

        if isinstance(location, Placeable):
            # give space for the drop-tip mechanism
            # @TODO (Laura & Andy 2018261)
            # When container typing is implemented, make sure that
            # when returning to a tiprack, tips are dropped within the rack
            if 'rack' in location.get_parent().get_type():
                half_tip_length = self._tip_length / 2
                location = location.top(-half_tip_length)
            elif 'trash' in location.get_parent().get_type():
                loc, coords = location.top()
                location = (loc, coords + (0, self.model_offset[1], 0))
            else:
                location = location.top()

        def _drop_tip(location, instrument=self):
            if location:
                self.move_to(location)

            pos_bottom = self._get_plunger_position('bottom')
            pos_drop_tip = self._get_plunger_position('drop_tip')

            self.instrument_actuator.set_active_current(self._plunger_current)
            self.robot.poses = self.instrument_actuator.move(
                self.robot.poses,
                x=pos_bottom
            )
            self.instrument_actuator.set_active_current(self._drop_tip_current)
            self.instrument_actuator.push_speed()
            self.instrument_actuator.set_speed(self._drop_tip_speed)
            self.robot.poses = self.instrument_actuator.move(
                self.robot.poses,
                x=pos_drop_tip
            )
            self.instrument_actuator.pop_speed()
            self._shake_off_tips(location)
            if home_after:
                self._home_after_drop_tip()

            self.current_volume = 0
            self.current_tip(None)
            self._remove_tip(
                length=self._tip_length
            )

        do_publish(self.broker, commands.drop_tip, self.drop_tip,
                   'before', None, None, self, location)
        _drop_tip(location)
        do_publish(self.broker, commands.drop_tip, self.drop_tip,
                   'after', self, None, self, location)
        return self