What is the clock on?
The clock is on the clock tower.
    src        edge_attr  dst
0     0   to the left of    4
1     0   to the left of   18
2     0  to the right of   14
3     0   to the left of    6
4     1  to the right of   12
5     1   to the left of   17
6     1  to the right of    6
7     3               on    4
8     4  to the right of    5
9     4  to the right of   10
10    4  to the right of   14
11    4  to the right of    0
12    4   to the left of   17
13    4  to the right of   13
14    5   to the left of    4
15    5   to the left of   19
16    6  to the right of   13
17    6   to the left of   17
18    6  to the right of    0
19    6   to the left of    1
20    6   to the left of    9
21    6  to the right of   14
22    6               on    4
23    6   to the left of   18
24    8               on    4
25    9  to the right of   13
26    9  to the right of    6
27   10   to the left of   11
28   10   to the left of    4
29   10   to the left of   18
30   11  to the right of   10
31   11   to the left of   18
32   11  to the right of   13
33   12   to the left of    1
34   13   to the left of    4
35   13   to the left of    9
36   13   to the left of    6
37   13   to the left of   18
38   13   to the left of   11
39   13   to the left of   15
40   14   to the left of    0
41   14   to the left of    6
42   14   to the left of    4
43   15   to the left of   16
44   15  to the right of   13
45   16  to the right of   15
46   17               on    9
47   17  to the right of    6
48   17  to the right of    1
49   17  to the right of    4
50   18  to the right of   11
51   18  to the right of    0
52   18  to the right of   10
53   18  to the right of    6
54   18  to the right of   13
55   19  to the right of    5