BFE.dev solution for TypeScript puzzle
1. implement Partial<T>

Looking at the code example, we can see that Partial means turn each property to be optional.

To get the properties we can use keyof

type A = {
  a: number
  b: string
}

type C = keyof A // 'a' | 'b'

Then we can just use Mapped Type to map each type to optional by ?.

type MyPartial<T> = {
  [P in keyof T]?: T[P]
}