You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/krill/src/daemon/properties
    
    the code of the file until where you have to start completion: //! Runtime configuration settings and properties
//!
//! Uses an event-sourced structure so that:
//! - These can be shared between multiple nodes
//! - An audit trail is provid
    
    pub fn upgrade_krill_version(&self, krill_version: KrillVersion) -> KrillResult<()> {
        let cmd = PropertiesCommand::new(
            &self.main_key,
            None,
            PropertiesCommandDetails::UpgradeTo { krill_version },
            &self.system_actor,
        );
        self.store.command(cmd)?;
        Ok(())
    }