How to write transition bins for a N bit counter for covering valid transitions?

It is easy to write something for a 2 bit counter like

`bins valid_transition = {2'b00=>2'b01,2'b01=>2'b10,2'b10=>2'b11,2'b11=>2'b00};`

but how does one scale it for an N bit counter with a large N.

LFT
2
This code wonâ€™t compile since transitional bins are written within parenthesis

how does one scale it for an N bit counter with a large N

One possible solution is using **wildcard bins**

```
coverpoint( cntr ) // Assume bit[2:0] cntr;
{
wildcard bins valid_transition[] = ( 3'b??? => 3'b??? ); // Creates 64 dynamic bins
}
```