## Primitive types

    function method(x: number, y: string, z: boolean) {}
    function stringifyBasicValue(value: string | number) {}
    function add(one: any, two: any): number {
      return one + two;
    }

    const bar: number = 2;
    var barVar: number = 2;
    let barLet: number = 2;
    let isOneOf: number | boolean | string = foo;

## Keywords

    type UnionAlias = 1 | 2 | 3;
    opaque type ID = string;
    declare opaque type PositiveNumber: number;
    type Country = $Keys<typeof countries>;
    type RequiredProps = $Diff<Props, DefaultProps>;