How to verify a variable input before runbook execution

Hi,

My challenge is to verify a user’s input before she clicks ‘execute’ 

For example: I’ve created a variable named MyNumber with Data type = integer

I want to verify that the provided value should not be higher than 3

Using input type as Escript, I’ve tried:
if @@{MyNumber}@@ > 3:

    print(3)

But when executing the runbook I get the warning that I have a cyclic dependency and the input is not available.

Is there a way to achieve this input verification?

Thanks