Is there any sand or snow that is not dirty?
No, there is sand but it is dirty.
    src        edge_attr  dst
0     0   to the left of    7
1     1   to the left of    7
2     2  to the right of    4
3     4   to the left of   14
4     4   to the left of    2
5     6   to the left of   18
6     6   to the left of   13
7     6   to the left of   15
8     7  to the right of    0
9     7  to the right of    1
10    8  to the right of   17
11   11   to the left of   15
12   11   to the left of   13
13   13  to the right of   11
14   13   to the left of   17
15   13  to the right of    6
16   14  to the right of    4
17   14  to the right of   17
18   15  to the right of    6
19   15  to the right of   11
20   17   to the left of   14
21   17  to the right of   13
22   17   to the left of    8
23   18  to the right of    6