What are the houses surrounded by?
The houses are surrounded by the trees.
    src        edge_attr  dst
0     0            below   16
1     0   to the left of    8
2     1   to the left of    7
3     1   to the left of   19
4     1    surrounded by   15
..  ...              ...  ...
58   19          next to    9
59   19   to the left of    7
60   19   to the left of   10
61   19  to the right of    1
62   19             near    9

[63 rows x 3 columns]