Some fanciful properties for clock

I have also tried with `eqc:collect/2` and it seems that we are not able to pick a number greater than or equals to 60 in relation to the generation of a 3-tuple. `eqc:collect/2` is not able to collect anything even with 20k generations.
If I choose `60` as generator we can collect values:
```
0% {3,60,5}
0% {2,60,46}
0% {2,60,33}
0% {2,60,23}
0% {2,60,17}
0% {2,60,10}
```
This is strange. :-)