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: configuration.rs
    path of file: ./repos/redismodule-rs/src
    
    the code of the file until where you have to start completion: use crate::context::thread_safe::{RedisGILGuard, RedisLockIndicator};
use crate::{raw, CallOptionResp, CallOptionsBuilder, CallResult, RedisValue};
use crate::{Context, RedisError, RedisString};
use bitflags::bitflags;
use std::ffi::{CStr, CString};
use std::marker::PhantomData;
use std::os::raw::{c_char, c_int, c_longlong, c_void};
use std::sync::atomic::{AtomicBool, AtomicI64, Ordering};
use std::sync::Mutex;

bitflags! {
    /// Configuration options
    pub struct ConfigurationFlags : u32 {
        /// The default flags for a config. This creates a config that can be modified after startup.
        const
    
    fn set_val(&self, name: *const c_char, val: G, err: *mut *mut raw::RedisModuleString) -> c_int {
        // we know the GIL is held so it is safe to use Context::dummy().
        let configuration_ctx = ConfigurationContext::new();
        if let Err(e) = self.variable.set(&configuration_ctx, val) {
            let error_msg = RedisString::create(None, e.to_string().as_str());
            unsafe { *err = error_msg.take() };
            return raw::REDISMODULE_ERR as i32;
        }
        let c_str_name = unsafe { CStr::from_ptr(name) };
        if let Some(v) = self.on_changed.as_ref() {
            v(
                &configuration_ctx,
                c_str_name.to_str().unwrap(),
                self.variable,
            )
        }
        raw::REDISMODULE_OK as i32
    }