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: iter_combinations.rs
    path of file: ./repos/bevy/examples/ecs
    
    the code of the file until where you have to start completion: //! Shows how to iterate over combinations of query results.

use bevy::{color::palettes::css::ORANGE_RED, prelude::*};
use rand::{rngs::StdRng, Rng, SeedableRng};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .insert_resource(ClearColor(Color::BLACK))
        .add_systems(Startup, generate_bodies)
        .add_systems(FixedUpdate, (interact_bodies, integrate))
        .add_systems(Update, look_at_star)
        .run();
}

const GRAVITY_CONSTANT:
    
fn interact_bodies(mut query: Query<(&Mass, &GlobalTransform, &mut Acceleration)>) {
    let mut iter = query.iter_combinations_mut();
    while let Some([(Mass(m1), transform1, mut acc1), (Mass(m2), transform2, mut acc2)]) =
        iter.fetch_next()
    {
        let delta = transform2.translation() - transform1.translation();
        let distance_sq: f32 = delta.length_squared();

        let f = GRAVITY_CONSTANT / distance_sq;
        let force_unit_mass = delta * f;
        acc1.0 += force_unit_mass * *m2;
        acc2.0 -= force_unit_mass * *m1;
    }
}