What are the doors made of?
The doors are made of metal.
    src        edge_attr  dst
0     0  to the right of    4
1     1  to the right of    4
2     2  to the right of    4
3     3  to the right of    4
4     4   to the left of    3
5     4   to the left of    2
6     4   to the left of    7
7     4   to the left of    1
8     4   to the left of    0
9     5            under    7
10    7          holding    1
11    7  to the right of    4
12    7   standing under    4
13    7      standing on    5
14    7            above    5
15    8           beside    5