What is the sidewalk made of?
The sidewalk is made of brick.
    src        edge_attr  dst
0     0   to the left of    2
1     0   to the left of    9
2     0  to the right of   12
3     1   to the left of    2
4     2  to the right of    1
5     2  to the right of    0
6     3   to the left of    6
7     6  to the right of    3
8     9               by    1
9     9  to the right of    0
10   10               on    9
11   10   to the left of   11
12   11  to the right of   10
13   11               by    1
14   12   to the left of    0