Typescript convert Nullable (null or undefined) to Partial / not required

NullableToPartial.ts

export type NullableToPartial<T> = T extends { [K: string]: any }
  ? {
      [K in keyof ({
        [K in NullableKeys<T>]?: T[K];
      } & {
        [K in RequiredKeys<T>]-?: T[K];
      })]: ({
        [K in NullableKeys<T>]?: T[K];
      } & {
        [K in RequiredKeys<T>]-?: T[K];
      })[K];
    }
  : never;

export type NullableKeys<T> = Extract<NullableByKind<T, 'nullable'>, string>;

export type RequiredKeys<T> = Extract<NullableByKind<T, 'required'>, string>;

export type NullableByKind<T, Kind extends 'nullable' | 'required'> = {
  [K in keyof T]?: IsNullable<T[K]> extends (
    Kind extends 'nullable' ? true : false
  )
    ? K
    : never;
}[keyof T] extends infer Temp
  ? Temp extends undefined
    ? never
    : Temp
  : never;