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: log.rs
    path of file: ./repos/toydb/src/raft
    
    the code of the file until where you have to start completion: use crate::error::{Error, Result};
use crate::storage::{self, bincode, keycode};

use ::log::debug;
u
    
    pub fn splice(&mut self, entries: Vec<Entry>) -> Result<Index> {
        if entries.is_empty() {
            return Ok(self.last_index);
        }
        if entries[0].index == 0 || entries[0].index > self.last_index + 1 {
            return Err(Error::Internal("Spliced entries must begin before last index".into()));
        }
        if entries[0].index <= self.commit_index {
            return Err(Error::Internal("Spliced entries must begin after commit index".into()));
        }
        if !entries.windows(2).all(|w| w[0].index + 1 == w[1].index) {
            return Err(Error::Internal("Spliced entries must be contiguous".into()));
        }
        let (last_index, last_term) = entries.last().map(|e| (e.index, e.term)).unwrap();

        // Skip entries that are already in the log (identified by index and term).
        let mut entries = entries.as_slice();
        let mut scan = self.scan(entries[0].index..=entries.last().unwrap().index)?;
        while let Some(e) = scan.next().transpose()? {
            if e.term != entries[0].term {
                break;
            }
            entries = &entries[1..];
        }
        drop(scan);

        // Write any entries not already in the log.
        for e in entries {
            self.engine
                .set(&Key::Entry(e.index).encode()?, bincode::serialize(&(&e.term, &e.command))?)?;
        }

        // Remove the remaining tail of the old log, if any, and update the index.
        for index in (last_index + 1)..=self.last_index {
            self.engine.delete(&Key::Entry(index).encode()?)?;
        }
        self.maybe_flush()?;
        self.last_index = last_index;
        self.last_term = last_term;
        Ok(self.last_index)
    }