the cell
contains a segment site, else false.</td>
          </tr>
          <tr>
            <td style="font-family: Courier New,Courier,monospace;">bool
            <span style="font-weight: bold;">is_degenerate</span>()
const </td>
            <td>Returns true if the cell
doesn't have an incident edge.<br>
Can happen if a few input segments share a common endpoint.</td>
          </tr>
        </tbody>
      </table>
      <span style="font-family: Courier New,Courier,monospace;"> </span>All
the above me