3 assert(sread(Map(), 2) == 0)

     2 def urbanmain() = {

     4 assert(sread(Map(2 -> 1), 2) == 1)

     3 

     5 assert(write(Map(), 1, 2) == Map(1 -> 2))

     4   import M5a._

     6 assert(write(Map(1 -> 0), 1, 2) == Map(1 -> 2))

     5 

     6   assert(sread(Map(), 2) == 0)

     7   assert(sread(Map(2 -> 1), 2) == 1)

     8   assert(write(Map(), 1, 2) == Map(1 -> 2))

     9   assert(write(Map(1 -> 0), 1, 2) == Map(1 -> 2))

    10 }