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: client.rs
    path of file: ./repos/ros2_rust/rclrs/src
    
    the code of the file until where you have to start completion: use std::boxed::Box;
use std::collections::HashMap;
use std::ffi::CString;
use std::sync::atomic::AtomicBool;
use std::sync::{Arc, Mutex, MutexGuard};

use futures::channel::oneshot;
use rosidl_runtime_rs::Message;

use crate::error::{RclReturnCode, ToResult};
use crate::MessageCow;
use crate::{rcl_bindings::*, RclrsError};

// SAFETY: The functions accessing this type, including drop(), shouldn't care about the thread
// they are running in. Therefore, this type can be safely sent to another thread.
unsafe impl Send for rcl_client_t {}

/// Internal struct used by cl
    
    pub fn take_response(&self) -> Result<(T::Response, rmw_request_id_t), RclrsError> {
        let mut request_id_out = rmw_request_id_t {
            writer_guid: [0; 16],
            sequence_number: 0,
        };
        type RmwMsg<T> =
            <<T as rosidl_runtime_rs::Service>::Response as rosidl_runtime_rs::Message>::RmwMsg;
        let mut response_out = RmwMsg::<T>::default();
        let handle = &*self.handle.lock();
        unsafe {
            // SAFETY: The three pointers are valid/initialized
            rcl_take_response(
                handle,
                &mut request_id_out,
                &mut response_out as *mut RmwMsg<T> as *mut _,
            )
        }
        .ok()?;
        Ok((T::Response::from_rmw_message(response_out), request_id_out))
    }