Kqueue.TimeoutKqueue.Timeout.t is the timespan in nanoseconds that is used to represent the maximum amount of time the kevent call should wait for an event.
val never : tnever results in the kevent call to wait indefinitely for a new event.
Note: Unlike Unix.select, if the user calls kevent with an empty eventlist, the kevent call returns immediately event when a timeout value of never is used.
val immediate : timmediate effects a poll, and the kevent call will return immediately, without waiting for new events if none are available at the time of the call.
val of_ns : int64 -> tof_ns creates a new timeout from nanoseconds.