const pickFunc = <T extends {}, K extends keyof T>(
    obj: T,
    predicate: (k: string) => boolean
): Pick<T, K> =>
    Object
        .keys(obj)
        .filter(predicate)
        .reduce((filteredObj: Pick<T, K>, key) => ({
            ...filteredObj,
            [key]: obj[key as keyof T]
        }), {} as Pick<T, K>)



// filters an object based on an array of keys
const pick = <T extends {}, K extends keyof T>(obj: T, keys: Array<K>): Pick<T, K> =>
    pickFunc(
        obj,
        k => keys.includes(k as K)
    )


const omit = <T extends {}, K extends keyof T>(obj: T, keys: Array<K>): Pick<T, K> =>
    pickFunc(
        obj,
        k => !keys.includes(k as K)
    )