;; CONTRACT map
FUNCTION make_empty_map():{map, integer, boolean}
  MAP_EMPTY a
  RETURN

FUNCTION map_update({map, integer, boolean}, integer, boolean):{map, integer, boolean}
  MAP_UPDATE a arg0 arg1 arg2
  RETURN

FUNCTION map_lookup({map, integer, boolean}, integer):boolean
  MAP_LOOKUP a arg0 arg1
  RETURN

FUNCTION map_lookup_default({map, integer, boolean}, integer): boolean
  MAP_LOOKUPD a arg0 arg1 false
  RETURN

FUNCTION map_member({map, integer, boolean}, integer):boolean
  MAP_MEMBER a arg0 arg1
  RETURN

FUNCTION map_delete({map, integer, boolean}, integer):{map, integer, boolean}
  MAP_DELETE a arg0 arg1
  RETURN

FUNCTION map_member({map, integer, boolean}, integer) : boolean
        MAP_MEMBER a arg0 arg1
        RETURN

FUNCTION map_from_list({list, {tuple, [integer, boolean]}}) : {map, integer, boolean}
        MAP_FROM_LIST a arg0
        RETURN