use crate::{alternate, compound, linked};use std::path::PathBuf; /// The error returned by [`linked::Db::at()`]#[derive(Debug, thiserror::Error)]#[allow(missing_docs)]pub enum Error {    #[error(transparent)]    CompoundDbInit(#[from] compound::init::Error),    #[error(transparent)]    AlternateResolve(#[from] alternate::Error),} impl linked::Db {    /// Instantiate an instance at the given `objects_directory`, commonly `.git/objects`.    ///    /// _git alternate_ files will be traversed to build a chain of [`compound::Db`] instances.    pub fn at(objects_directory: impl Into<PathBuf>) -> Result<Self, Error> {        let mut dbs = vec![compound::Db::at(objects_directory.into())?];        for object_path in alternate::resolve(dbs[0].loose.path.clone())?.into_iter() {            dbs.push(compound::Db::at(object_path)?);        }        assert!(            !dbs.is_empty(),            "we can rely on at least one compound database to be present"        );        Ok(linked::Db { dbs })    }} impl std::convert::TryFrom<PathBuf> for linked::Db {    type Error = Error;     fn try_from(value: PathBuf) -> Result<Self, Self::Error> {        linked::Db::at(value)    }}