use crate::OutputFormat;use anyhow::{Context as AnyhowContext, Result};use git_commitgraph::{graph::verify::Outcome, Graph};use std::{io, path::Path}; /// A general purpose context for many operations provided herepub struct Context<W1: io::Write, W2: io::Write> {    /// A stream to which to output errors    pub err: W2,    /// A stream to which to output operation results    pub out: W1,    pub output_statistics: Option<OutputFormat>,} impl Default for Context<Vec<u8>, Vec<u8>> {    fn default() -> Self {        Context {            err: Vec::new(),            out: Vec::new(),            output_statistics: None,        }    }} pub fn graph_or_file<W1, W2>(    path: impl AsRef<Path>,    Context {        err: _err,        mut out,        output_statistics,    }: Context<W1, W2>,) -> Result<git_commitgraph::graph::verify::Outcome>where    W1: io::Write,    W2: io::Write,{    let g = Graph::at(path).with_context(|| "Could not open commit graph")?;     #[allow(clippy::unnecessary_wraps, unknown_lints)]    fn noop_processor(_commit: &git_commitgraph::file::Commit<'_>) -> std::result::Result<(), std::fmt::Error> {        Ok(())    }    let stats = g        .verify_integrity(noop_processor)        .with_context(|| "Verification failure")?;     match output_statistics {        Some(OutputFormat::Human) => drop(print_statistics(&mut out, &stats)),        #[cfg(feature = "serde1")]        Some(OutputFormat::Json) => serde_json::to_writer_pretty(out, &stats)?,        _ => {}    }     Ok(stats)} fn print_statistics(out: &mut impl io::Write, stats: &Outcome) -> io::Result<()> {    writeln!(out, "number of commits with the given number of parents")?;    let mut parent_counts: Vec<_> = stats.parent_counts.iter().map(|(a, b)| (*a, *b)).collect();    parent_counts.sort_by_key(|e| e.0);    for (parent_count, commit_count) in parent_counts.into_iter() {        writeln!(out, "\t{:>2}: {}", parent_count, commit_count)?;    }    writeln!(out, "\t->: {}", stats.num_commits)?;     write!(out, "\nlongest path length between two commits: ")?;    if let Some(n) = stats.longest_path_length {        writeln!(out, "{}", n)?;    } else {        writeln!(out, "unknown")?;    }     Ok(())}