(bridge-lanes bridge) -> channel
Given a bridge, return a channel from which created lanes can be obtained.
>> (define a (make-channel)) :: [channel 573450] >> (define b (make-channel)) :: [channel 53FDE0] >> (define br (make-bridge a b)) :: [bridge [vector [dict] [dict] [channel 574310] [channel 574340] [channel 573450] [channel 53FDE0]]] >> (bridge-lanes br) :: [channel 574340]