/// # fn write(&self, namespace: &str, key: &str, buf: &[u8]) -> io::Result<()> { Ok(()) }
/// # fn remove(&self, namespace: &str, key: &str) -> io::Result<()> { Ok(()) }
/// # fn list(&self, namespace: &str) -> io::Result<Vec<String>> { Ok(Vec::new()) }
/// # fn write(&self, namespace: &str, key: &str, buf: &[u8]) -> io::Result<()> { Ok(()) }
/// # fn remove(&self, namespace: &str, key: &str) -> io::Result<()> { Ok(()) }
/// # fn list(&self, namespace: &str) -> io::Result<Vec<String>> { Ok(Vec::new()) }