If this were a game, we&apos;d define each category with a unique binary digit, or bit, so let&apos;s first do that:</p>
<table>
<thead>
<tr>
<th>entity</th>
<th>category</th>
</tr>
</thead>
<tbody>
<tr>
<td>sun</td>
<td>0000</td>
</tr>
<tr>
<td>player</td>
<td>0001</td>
</tr>
<tr>
<td>powerup</td>
<td>0010</td>
</tr>
<tr>
<td>enemy</td>
<td>0100</td>
</tr>
<tr>
<td>ground</td>
<td>1000</td>
</tr>
</tbody>
</table>
<p>Let&apos;s set some rules for each of these entities.
For instance, we want the player to 