Resource
pollable
pollable represents a single I/O event which may be ready, or not.
resource pollable;F ready
ready: func() -> bool;Return the readiness of a pollable. This function never blocks.
Returns true when the pollable is ready, and false otherwise.
F block
block: func();block returns immediately if the pollable is ready, and otherwise
blocks until ready.
This function is equivalent to calling poll.poll on a list
containing only this pollable.