Macro parse_openssh 

macro_rules! parse_openssh {
    (PRIVATE $key:expr, $key_type:expr) => { ... };
    (PUBLIC $key:expr, $key_type:expr) => { ... };
    ($key:expr, $key_type:expr, $parse_fn:path) => { ... };
}

Parse an OpenSSH key, returning its corresponding SshKeyData.