pi = 3 # sorry --- the checker handles int only )-: def circ(diameter) : """{ pre diameter >= 0 and pi >= 3 post answer == pi * diameter return answer }""" answer = pi * diameter return answer """{ 1.OK pi == 3 premise 2.OK pi >= 3 algebra 1 }""" x = circ(2) """{ 1.OK x == pi * 2 premise }"""