What material is the window?
The window is made of metal.
   src        edge_attr  dst
0    0  to the right of    1
1    1   to the left of    0
2    1   to the left of    2
3    2   to the left of    3
4    2  to the right of    1
5    3  to the right of    5
6    3  to the right of    2
7    4  to the right of    6
8    5   to the left of    3
9    6   to the left of    4