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: extensions.rs
    path of file: ./repos/glium/src/context
    
    the code of the file until where you have to start completion: use crate::gl;
use crate::version::Api;
use crate::version::Version;
use std::ffi::CStr;

macro_rules! extensions {
    ($($string:expr => $field:ident,)+) => {
        /// Contains data about the list of extensions.
        #[derive(Debug, Clone, Copy)]
        pub struct ExtensionsList {
            $(
    
    
unsafe fn get_extensions_strings(gl: &gl::Gl, version: &Version) -> Vec<String> {
    if version >= &Version(Api::Gl, 3, 0) || version >= &Version(Api::GlEs, 3, 0) {
        let mut num_extensions = 0;
        gl.GetIntegerv(gl::NUM_EXTENSIONS, &mut num_extensions);

        (0 .. num_extensions).map(|num| {
            let ext = gl.GetStringi(gl::EXTENSIONS, num as gl::types::GLuint);
            String::from_utf8(CStr::from_ptr(ext as *const _).to_bytes().to_vec()).unwrap()
        }).collect()

    } else {
        let list = gl.GetString(gl::EXTENSIONS);
        assert!(!list.is_null());
        let list = String::from_utf8(CStr::from_ptr(list as *const _).to_bytes().to_vec())
                                     .unwrap();
        list.split(' ').map(|e| e.to_owned()).collect()
    }
}