I want to use galapagos to do some optimization. One of the parameters to optimize is the thickness of a concrete deck. The thickness is given in mm. the minimum amount is set to 10 mm and the maximum is set to 50 mm. It doesnt make sense to optimize every value in that range since it is almost impossible to pour concrete with mm accuracy. therefore i want galapagos to only look at 10, 15, 20 etc.mm. How do i program this?