pub fn positive(s: &str) -> Result<usize, String>Expand description
A count of things, which must be at least one.
Not bytes(): a queue depth of 4k would read as 4,096 there and mean 4,000
to whoever typed it, and a slot is not a byte. Zero is refused rather than
silently meaning “rendezvous channel”, which is what mpsc::channel(0) would
panic on and what an operator typing it would never intend.