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: global.rs
    path of file: ./repos/wasmtime/crates/wasmtime/src/runtime/externals
    
    the code of the file until where you have to start completion: use crate::{
    store::{AutoAssertNoGc, StoreData, StoreOpaque, Stored},
    trampoline::generate_global_export,
    AsContext, AsContextMut, ExternRef, Func, GlobalType, HeapType, Mutability, Ref, Val, ValType,
};
use anyhow::{bail, Context, Result};
use std::mem;
use std::ptr;

/// A WebAssembly `global` value which can be read and written to.
///
/// A `global` in WebAssembly is sort of like a global variable within an
/// [`Instance`](crate::Instance). The `global.get` and `global.set`
/// instructions will modify and read global values in a wasm module. Globals
/// can either be imported or exported from wasm modules.
///
/// A [`Global`] "belongs" to the store that it was originally created within
/// (either via [`Global::new`] or via instantiating a
/// [`Module`](crate::Module)). Operations on a [`Global`] only work with the
/// store it belongs to, and if another store is passed 
    
    fn hash_key_is_stable_across_duplicate_store_data_entries() -> Result<()> {
        let mut store = Store::<()>::default();
        let module = Module::new(
            store.engine(),
            r#"
                (module
                    (global (export "g") (mut i32) (i32.const 0))
                )
            "#,
        )?;
        let instance = Instance::new(&mut store, &module, &[])?;

        // Each time we `get_global`, we call `Global::from_wasmtime` which adds
        // a new entry to `StoreData`, so `g1` and `g2` will have different
        // indices into `StoreData`.
        let g1 = instance.get_global(&mut store, "g").unwrap();
        let g2 = instance.get_global(&mut store, "g").unwrap();

        // That said, they really point to the same global.
        assert_eq!(g1.get(&mut store).unwrap_i32(), 0);
        assert_eq!(g2.get(&mut store).unwrap_i32(), 0);
        g1.set(&mut store, Val::I32(42))?;
        assert_eq!(g1.get(&mut store).unwrap_i32(), 42);
        assert_eq!(g2.get(&mut store).unwrap_i32(), 42);

        // And therefore their hash keys are the same.
        assert!(g1.hash_key(&store.as_context().0) == g2.hash_key(&store.as_context().0));

        // But the hash keys are different from different globals.
        let instance2 = Instance::new(&mut store, &module, &[])?;
        let g3 = instance2.get_global(&mut store, "g").unwrap();
        assert!(g1.hash_key(&store.as_context().0) != g3.hash_key(&store.as_context().0));

        Ok(())
    }