What is the color of the device in the bottom?
The charger is black.
   src        edge_attr  dst
0    1  to the right of    5
1    2  to the right of    3
2    3   to the left of    2
3    3  to the right of    4
4    4               on    0
5    4   to the left of    3
6    5   to the left of    1