// We can quickly address your report if:
//  - The code sample is short. Nearly all TypeScript bugs can be demonstrated in 20-30 lines of code!
//  - It doesn't use external libraries. These are often issues with the type definitions rather than TypeScript bugs.
//  - The incorrectness of the behavior is readily apparent from reading the sample.
// Reports are slower to investigate if:
//  - We have to pare too much extraneous code.
//  - We have to clone a large repo and validate that the problem isn't elsewhere.
//  - The sample is confusing or doesn't clearly demonstrate what's wrong.
interface Mapper<T = any, R = any> {
    (arg: T): R;
}

function pick<O, T extends keyof O>(keys: T[], obj?: O): Pick<O, T>;
function pick<T>(keys: T[]): Mapper;
function pick<O, T extends keyof O>(keys: T[], obj?: O) {
    const picker: Mapper<O, { [K in T]: O[T] }> = _obj => Object.entries(_obj).reduce((o, [key, val]) => {
        if (keys.includes(key as T)) o[key as T] = val;
        return o;
    }, {} as Pick<O, T>);

    return obj ? picker(obj) : picker;
}

const { a, b } = pick(['b'], { a: 'a', b: 'b' }) //here the autosuggest should show b only
const obj = pick(['b'], { a: 'a', b: 'b' })
obj.a // here it is working properly as you can only select b