Instance

    const Instance = struct {
        thread: WasiThread,
        /// Contains the offset to the new __tls_base.
        /// The offset starting from the memory's base.
        tls_offset: usize,
        /// Contains the offset to the stack for the newly spawned thread.
        /// The offset is calculated starting from the memory's base.
        stack_offset: usize,
        /// Contains the raw pointer value to the wrapper which holds all arguments
        /// for the callback.
        raw_ptr: usize,
        /// Function pointer to a wrapping function which will call the user's
        /// function upon thread spawn. The above mentioned pointer will be passed
        /// to this function pointer as its argument.
        call_back: *const fn (usize) void,
        /// When a thread is in `detached` state, we must free all of its memory
        /// upon thread completion. However, as this is done while still within
        /// the thread, we must first jump back to the main thread's stack or else
        /// we end up freeing the stack that we're currently using.
        original_stack_pointer: [*]u8,
    }