.ts dynamic static diff

// the `unknown` type is similar to `any`, except it is less permissive on the RHS of assignment
let unknownType: unknown = 'asdf'
let anyType: any = 'asdf';
let someString: string;
// now,
someString = anyType;
// is permitted, while
//     someString = unknownType
// errors

// by the way, note that it's possible to have the dynamic and static types
// _of the same variable_ differ because of the permissiveness of the 'any'
// type on the RHS of assignment.
anyType = 1
someString = anyType;
console.log(typeof someString); // 'number'