Which color do you think the ground is?
The ground is black.
    src        edge_attr  dst
0     0   to the left of    9
1     0   to the left of    3
2     0   to the left of    2
3     1  to the right of    3
4     1  to the right of   11
5     2  to the right of    5
6     2  to the right of    0
7     3               by   11
8     3          pulling   10
9     3  to the right of    0
10    3   to the left of    1
11    3  to the right of    4
12    3  to the right of    5
13    3          helping    2
14    4   to the left of    3
15    5   to the left of    3
16    5   to the left of    2
17    9  to the right of    0
18   10        pulled by    3
19   11   to the left of    1