use crate::borrowed;use bstr::{BStr, ByteSlice}; /// An iterator over extra headers in [owned][crate::owned::Commit] and [borrowed][borrowed::Commit] commits.pub struct ExtraHeaders<I> {    inner: I,} /// Instantiation and convenience.impl<'a, I> ExtraHeaders<I>where    I: Iterator<Item = (&'a BStr, &'a BStr)>,{    /// Create a new instance from an iterator over tuples of (name, value) pairs.    pub fn new(iter: I) -> Self {        ExtraHeaders { inner: iter }    }    /// Find the _value_ of the _first_ header with the given `name`.    pub fn find(mut self, name: &str) -> Option<&'a BStr> {        self.inner            .find_map(move |(k, v)| if k == name.as_bytes().as_bstr() { Some(v) } else { None })    }    /// Return an iterator over all _values_ of headers with the given `name`.    pub fn find_all(self, name: &'a str) -> impl Iterator<Item = &'a BStr> {        self.inner            .filter_map(move |(k, v)| if k == name.as_bytes().as_bstr() { Some(v) } else { None })    }    /// Return an iterator over all git mergetags.    ///    /// A merge tag is a tag object embedded within the respective header field of a commit, making    /// it a child object of sorts.    pub fn mergetags(self) -> impl Iterator<Item = Result<borrowed::Tag<'a>, borrowed::Error>> {        self.find_all("mergetag").map(|b| borrowed::Tag::from_bytes(b))    }     /// Return the cryptographic signature provided by gpg/pgp verbatim.    pub fn pgp_signature(self) -> Option<&'a BStr> {        self.find("gpgsig")    }}