How to use the dulwich.objects.Commit function in dulwich

def step_impl_given(context):
    context.test_git_repo_dir = tempfile.mkdtemp("paasta_tools_deployments_json_itest")
    context.test_git_repo = Repo.init(context.test_git_repo_dir)
    paasta_print("Temp repo in %s" % context.test_git_repo_dir)

    blob = Blob.from_string(b"My file content\n")
    tree = Tree()
    tree.add(b"spam", 0o0100644, blob.id)

    commit = Commit()
    commit.author = commit.committer = b"itest author"
    commit.commit_time = commit.author_time = int(time())
    commit.commit_timezone = commit.author_timezone = parse_timezone(b"-0200")[0]
    commit.message = b"Initial commit"
    commit.tree = tree.id

    object_store = context.test_git_repo.object_store
    object_store.add_object(blob)
    object_store.add_object(tree)
    object_store.add_object(commit)

    context.test_git_repo.refs[b"refs/heads/master"] = commit.id
    context.expected_commit_as_bytes = commit.id
    context.expected_commit = context.expected_commit_as_bytes.decode()

def create_commit(data, marker=b'Default', blob=None):
    if not blob:
        blob = Blob.from_string(b'The blob content ' + marker)
    tree = Tree()
    tree.add(b"thefile_" + marker, 0o100644, blob.id)
    cmt = Commit()
    if data:
        assert isinstance(data[-1], Commit)
        cmt.parents = [data[-1].id]
    cmt.tree = tree.id
    author = b"John Doe " + marker + b" "
    cmt.author = cmt.committer = author
    tz = parse_timezone(b'-0200')[0]
    cmt.commit_time = cmt.author_time = int(time())
    cmt.commit_timezone = cmt.author_timezone = tz
    cmt.encoding = b"UTF-8"
    cmt.message = b"The commit message " + marker
    tag = Tag()
    tag.tagger = b"john@doe.net"
    tag.message = b"Annotated tag"
    tag.tag_timezone = parse_timezone(b'-0200')[0]
    tag.tag_time = cmt.author_time
    tag.object = (Commit, cmt.id)
    tag.name = b"v_" + marker + b"_0.1"

))
    tree = repo.object_store[repo.object_store[parent_commit_id].tree]

    # get setup.py
    setuppy_mode, setuppy_id = tree['setup.py']
    setuppy = repo.object_store[setuppy_id]

    release_setup = Blob.from_string(replace_version(setuppy.data, 'version',
                                     str(new_version)))
    tree['setup.py'] = (setuppy_mode, release_setup.id)

    objects_to_add.append(release_setup)
    objects_to_add.append(tree)

    now = int(time.time())
    new_commit = Commit()
    new_commit.parents = [parent_commit_id]

    new_commit.tree = tree.id

    new_commit.author = author
    new_commit.committer = author

    new_commit.commit_time = now
    new_commit.author_time = now

    now = int(time.time())
    offset = tzlocal().utcoffset(datetime.utcfromtimestamp(now))
    timezone = offset.days * 24 * 60 * 60 + offset.seconds
    new_commit.commit_timezone = timezone
    new_commit.author_timezone = timezone

def commit_handler(self, cmd):
        """Process a CommitCommand."""
        commit = Commit()
        if cmd.author is not None:
            author = cmd.author
        else:
            author = cmd.committer
        (author_name, author_email, author_timestamp, author_timezone) = author
        (committer_name, committer_email, commit_timestamp,
            commit_timezone) = cmd.committer
        commit.author = author_name + b" <" + author_email + b">"
        commit.author_timezone = author_timezone
        commit.author_time = int(author_timestamp)
        commit.committer = committer_name + b" <" + committer_email + b">"
        commit.commit_timezone = commit_timezone
        commit.commit_time = int(commit_timestamp)
        commit.message = cmd.message
        commit.parents = []
        if cmd.from_:

#make the blob
                blob = Blob.from_string(content)
                
                repo = Repo(self.package.path())
                #change to the right branch
                last_head = repo.head()
                set_head(repo, "master")
                last_commit = repo.get_object(repo.head())
                tree = repo.tree(repo.get_object(repo.head()).tree)

                #set the file
                tree[self.filename] = (0100644, blob.id)
                
                #make the commit
                commit = Commit()
                commit.tree = tree.id
                commit.parents = [last_head]
                commit.author = commit.committer = username
                commit.commit_time = commit.author_time = int(time.time())
                commit.commit_timezone = commit.author_timezone = parse_timezone("-0600")
                commit.encoding = "UTF-8"
                commit.message = "not implemented yet"

                repo.object_store.add_object(blob)
                repo.object_store.add_object(tree)
                repo.object_store.add_object(commit)
                repo.refs["refs/heads/" + branch] = commit.id
                repo.refs["HEAD"] = "ref: refs/heads/" + branch
                new_link = "<a href="\&quot;/package/&quot;">go to the new version</a>"
                self.new_link = new_link

def parse_patch_message(msg, encoding=None):
    """Extract a Commit object and patch from an e-mail message.

    Args:
      msg: An email message (email.message.Message)
      encoding: Encoding to use to encode Git commits
    Returns: Tuple with commit object, diff contents and git version
    """
    c = Commit()
    c.author = msg["from"].encode(encoding)
    c.committer = msg["from"].encode(encoding)
    try:
        patch_tag_start = msg["subject"].index("[PATCH")
    except ValueError:
        subject = msg["subject"]
    else:
        close = msg["subject"].index("] ", patch_tag_start)
        subject = msg["subject"][close+2:]
    c.message = (subject.replace("\n", "") + "\n").encode(encoding)
    first = True

    body = msg.get_payload(decode=True)
    lines = body.splitlines(True)
    line_iter = iter(lines)

def export_hg_commit(self, rev, exporter):
        self.ui.note(_("converting revision %s\n") % hex(rev))

        oldenc = self.swap_out_encoding()

        ctx = self.repo.changectx(rev)
        extra = ctx.extra()

        commit = Commit()

        (time, timezone) = ctx.date()
        # work around to bad timezone offets - dulwich does not handle
        # sub minute based timezones. In the one known case, it was a
        # manual edit that led to the unusual value. Based on that,
        # there is no reason to round one way or the other, so do the
        # simplest and round down.
        timezone -= timezone % 60
        commit.author = self.get_git_author(ctx)
        commit.author_time = int(time)
        commit.author_timezone = -timezone

        if "committer" in extra:
            try:
                # fixup timezone
                (name, timestamp, timezone) = extra["committer"].rsplit(" ", 2)

trees.append(obj)
                        tree = obj
                except KeyError:
                    break
            # Cut down the blob and all rotten trees on the way back...
            for path, tree in reversed(zip(paths, trees)):
                del tree[path]
                if tree:
                    # This tree still has elements - don't remove it or any
                    # of it's parents
                    break

        object_store.add_object(commit_tree)

        # Create commit
        commit = objects.Commit()
        commit.tree = commit_tree.id
        commit.parents = [p._commit.id for p in self.parents if p]
        commit.author = commit.committer = safe_str(author)
        commit.encoding = ENCODING
        commit.message = safe_str(message)

        # Compute date
        if date is None:
            date = time.time()
        elif isinstance(date, datetime.datetime):
            date = time.mktime(date.timetuple())

        author_time = kwargs.pop('author_time', date)
        commit.commit_time = int(date)
        commit.author_time = int(author_time)
        tz = time.timezone

gitsha = handler.map_git_get(hgctx.hex())
    if not gitsha:
        # TODO deal better with commits in the middle of octopus merges
        raise hgutil.Abort(
            _("no git commit found for rev %s") % hgctx,
            hint=_("if this is an octopus merge, " "verify against the last rev"),
        )

    try:
        gitcommit = handler.git.get_object(gitsha)
    except KeyError:
        raise hgutil.Abort(
            _("git equivalent %s for rev %s not found!") % (gitsha, hgctx)
        )
    if not isinstance(gitcommit, Commit):
        raise hgutil.Abort(
            _("git equivalent %s for rev %s is not a commit!") % (gitsha, hgctx)
        )

    ui.status(_("verifying rev %s against git commit %s\n") % (hgctx, gitsha))
    failed = False

    # TODO check commit message and other metadata

    dirkind = stat.S_IFDIR

    hgfiles = set(hgctx)
    gitfiles = set()

    i = 0
    with progress.bar(ui, _("verify"), total=len(hgfiles)) as prog:

"""Print the changes in a commit.

    :param repo: Path to repository
    :param objects: Objects to show (defaults to [HEAD])
    :param outstream: Stream to write to
    :param default_encoding: Default encoding to use if none is set in the
        commit
    """
    if objects is None:
        objects = ["HEAD"]
    if not isinstance(objects, list):
        objects = [objects]
    with open_repo_closing(repo) as r:
        for objectish in objects:
            o = parse_object(r, objectish)
            if isinstance(o, Commit):
                def decode(x):
                    return commit_decode(o, x, default_encoding)
            else:
                def decode(x):
                    return x.decode(default_encoding)
            show_object(r, o, decode, outstream)