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/ckb/spec/src/versionbits
    
    the code of the file until where you have to start completion: //! Versionbits defines a finite-state-machine to deploy a softfork in multiple stages.
//!

mod convert;

use crate::consensus::Consensus;
use ckb_logger::error;
use ckb_types::global::DATA_DIR;
use ckb_types::{
    core::{EpochExt, EpochNumber, HeaderView, Ratio, TransactionView, Vers
    
    pub fn get(&self, key: &Byte32) -> Option<ThresholdState> {
        match cacache::read_sync(&self.path, Self::encode_key(key)) {
            Ok(bytes) => Some(Self::decode_value(bytes)),
            Err(cacache::Error::EntryNotFound(_path, _key)) => None,
            Err(err) => {
                error!("cacache read_sync failed {:?}", err);
                None
            }
        }
    }