adam@1527: structure M = struct
adam@1527:     con num = int
adam@1527:     val zero = 0
adam@1527: end
adam@1527: 
adam@1527: structure N = struct
adam@1527:     open M
adam@1527:     con num = num * num
adam@1527:     val zero = zero + 1
adam@1527: end
adam@1527: 
adam@1527: structure O = struct
adam@1527:     open N
adam@1527: 
adam@1527:     val one : num = (zero + 1, zero)
adam@1527: end