You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: inventory_system.rs
    path of file: ./repos/rustrogueliketutorial/chapter-21-rexmenu/src
    
    the code of the file until where you have to start completion: use specs::prelude::*;
use super::{WantsToPickupItem, Name, InBackpack, Position, gamelog::GameLog, WantsToUseItem,
    Consumable, ProvidesHealing, CombatStats, WantsToDropItem, InflictsDamage, Map, SufferDamage,
    AreaOfEffect, Confusion, Equippable, Equipped, WantsToRemoveItem, particle_
    
    fn run(&mut self, data : Self::SystemData) {
        let (player_entity, mut gamelog, entities, mut wants_drop, names, mut positions, mut backpack) = data;

        for (entity, to_drop) in (&entities, &wants_drop).join() {
            let mut dropper_pos : Position = Position{x:0, y:0};
            {
                let dropped_pos = positions.get(entity).unwrap();
                dropper_pos.x = dropped_pos.x;
                dropper_pos.y = dropped_pos.y;
            }
            positions.insert(to_drop.item, Position{ x : dropper_pos.x, y : dropper_pos.y }).expect("Unable to insert position");
            backpack.remove(to_drop.item);

            if entity == *player_entity {
                gamelog.entries.push(format!("You drop the {}.", names.get(to_drop.item).unwrap().name));
            }
        }

        wants_drop.clear();
    }