System.PoolSourceval use :
?priority:??? ->
('a -> ('b, 'e) result System_core.Fiber.t) ->
('a, 'e) t ->
('b, 'e) result System_core.Fiber.tval create :
?config:??? ->
?check:??? ->
?validate:??? ->
?log_src:??? ->
sw:System_core.Switch.t ->
stdenv:System_core.stdenv ->
(unit -> ('a, 'e) result System_core.Fiber.t) ->
('a -> unit System_core.Fiber.t) ->
('a, 'e) t