Function typeIs

typeIs<T>(value, type): value is CheckableTypes[T]
Returns true if typeof(value) == type, otherwise false. This function allows for type narrowing. i.e.
```
// v is unknown
if (typeIs(v, "Vector3")) {
    // v is a Vector3
    print(v.X, v.Y, v.Z);
}
```
Type Parameters
- T extends keyof CheckableTypes
Parameters
- value: any
- type: T
Returns value is CheckableTypes[T]