Concurrency limitation

Concurrency limitation:

import CPromise from "c-promise2";
import cpFetch from "cp-fetch";

(async()=>{
    await CPromise.all([
        'url1',
        'url2',
        'url3',
        'url4',
        'url5',
        'url6',
    ], {
        mapper: async (url) => {
            return cpFetch(url);
        },
        concurrency: 2
    })
    console.log('Done');
});

// Or

(async()=>{
    await CPromise.all(function*(){
        const urls= [
           'url1',
           'url2',
           'url3',
           'url4',
           'url5',
           'url6',
        ];
        for(let url of urls){
            yield cpFetch('url1');
        }
    }, {
        concurrency: 2
    })
    console.log('Done');
})();