pub fn take<C: CommandFactory>(default_bin: &str) -> Option<ExitCode>Available on crate feature
usage only.Expand description
If the process argv asks for --usage-spec[=BIN], print the spec of C to
stdout and return the exit code to end with.
default_bin names the task when the flag has no =BIN. The result is
ExitCode::SUCCESS when the write worked and ExitCode::FAILURE
otherwise, and None when argv has no such flag.