TSpawnResult = enum
  srVoid, srFlowVar, srByVar

proc spawnResult(t: PType; inParallel: bool): TSpawnResult {.
    ...raises: [Exception], tags: [RootEffect].}

proc wrapProcForSpawn(g: ModuleGraph; idgen: IdGenerator; owner: PSym;
                      spawnExpr: PNode; retType: PType;
                      barrier, dest: PNode = nil): PNode {....raises: [Exception,
    ValueError, KeyError, OSError, IOError, ERecoverableError], tags: [
    RootEffect, ReadDirEffect, WriteIOEffect, ReadIOEffect, ReadEnvEffect].}