What's the pencil made of?
The pencil is made of wood.
    src        edge_attr  dst
0     0               on    6
1     0  to the right of    3
2     0  to the right of    1
3     1   to the left of    0
4     2               on    6
5     3   to the left of    0
6     3               on    6
7     3            below    4
8     4            above    3
9     5               on    6
10    7        on top of    2
11    7               on    6