*-C
  |
*-B
| |
| *-C---D
|
A
|
*---B
|
*-B---C

A

      *-D---E---F
      |
      |         *-G
      |         |
      |       *-F---G
      |       | |
*-B   *---D---E *-G
|     |       |
A     *-----D *-F---G
|     |
*-B---C
      |
      *---D
      |
      | *-E
      | |
      | *---E
      | |
      | *-----E---F
      | |
      *-D
        |
        *-----E
        |
        *---E
        |
        *-E