What's the bridge made of?
The bridge is made of wood.
    src        edge_attr  dst
0     0  to the right of    7
1     0  to the right of    2
2     1  to the right of    9
3     1  to the right of    7
4     2   to the left of    0
5     2               on    6
6     3  to the right of    6
7     5  to the right of    8
8     6   to the left of    3
9     7   to the left of    0
10    7               of    2
11    7   to the left of    1
12    7  to the right of    9
13    8   to the left of    5
14    9   to the left of    1
15    9   to the left of    7
16    9               of    2