Returns a an object transformed into a new shape provided via callback function.
function objectInto<T extends object, K extends keyof T, V extends T[K]>(
obj: T,
fn: (key: K, val: V) => object
)
// Example:
const obj = { user: { id: 1, name: "Stephen", age: 39, sex: "M"} }
into(obj, (key, value) => ({[value.name]: `${value.age}/${value.sex}`}))
//=> { "Stephen": "39/M" }