<p>
  Sometimes you need to store lots of diffrent state about a type.
  Usualy that it has something or not. It would be wastefull to
  use for each feature a single value. The more effitient way is
  to store it using flags.
</p>
<p>
  To do that, you can use enums. You just have to assigne the values, such that
  only one bit is ever set and no member shares a bit.
  You can then set multiple flags by or-ing them together using |-operator.
  To check, if a flag is set, use the &-operator.
</p>
<p>
  Implement a <it>Set</it> and <it>isSet</it> function to make these operations more readable.
</p>