Which place is it?
It is an airport.
    src        edge_attr  dst
0     0  to the right of    4
1     3  to the right of   18
2     3  to the right of   11
3     4   to the left of    0
4     5   to the left of   12
5     5   to the left of   17
6     6  to the right of   16
7     7  to the right of   17
8     7  to the right of   18
9     7  to the right of   12
10   11   to the left of    3
11   12   to the left of    7
12   12  to the right of    5
13   12   to the left of   17
14   16   to the left of    6
15   17   to the left of    7
16   17  to the right of    5
17   17  to the right of   12
18   17  to the right of   18
19   18   to the left of    3
20   18   to the left of   17
21   18   to the left of    7