How to use the dulwich.objects function in dulwich

for f in files:
            open(os.path.join(self.temp_d, f), 'w').write("DATA %s" % i)
            i += 1
        local_repo.stage(files)
        local_repo.do_commit('Test commit', 'fbo@localhost',
                             ref='refs/heads/master')
        swift.SwiftRepo.init_bare(self.scon, self.conf)
        tcp_client = client.TCPGitClient(self.server_address,
                                         port=self.port)
        tcp_client.send_pack(self.fakerepo,
                             determine_wants,
                             local_repo.object_store.generate_pack_data)
        swift_repo = swift.SwiftRepo("fakerepo", self.conf)
        commit_sha = swift_repo.refs.read_loose_ref('refs/heads/master')
        otype, data = swift_repo.object_store.get_raw(commit_sha)
        commit = objects.ShaFile.from_raw_string(otype, data)
        otype, data = swift_repo.object_store.get_raw(commit._tree)
        tree = objects.ShaFile.from_raw_string(otype, data)
        objs = tree.items()
        objs_ = []
        for tree_entry in objs:
            objs_.append(swift_repo.object_store.get_raw(tree_entry.sha))
        # Blob
        self.assertEqual(objs_[1][1], 'DATA 0')
        self.assertEqual(objs_[2][1], 'DATA 1')
        # Tree
        self.assertEqual(objs_[0][0], 2)

def make_commit(repo, tree, message, author, timezone, encoding="UTF-8"):
    """build a Commit object"""
    commit = Commit()
    try:
        commit.parents = [repo.head()]
    except KeyError:
        #the initial commit has no parent
        pass
    if isinstance(tree, dulwich.objects.Tree): tree_id = tree.id
    elif isinstance(tree, str): tree_id = tree
    commit.tree = tree_id
    commit.message = message
    commit.author = commit.committer = author
    commit.commit_time = commit.author_time = int(time())
    commit.commit_timezone = commit.author_timezone = parse_timezone(timezone)
    commit.encoding = encoding
    return commit

def tree_entry(fctx, blob_cache):
        """Compute a dulwich TreeEntry from a filectx.

        A side effect is the TreeEntry is stored in the passed cache.

        Returns a 2-tuple of (dulwich.objects.TreeEntry, dulwich.objects.Blob).
        """
        blob_id = blob_cache.get(fctx.filenode(), None)
        blob = None

        if blob_id is None:
            blob = dulobjs.Blob.from_string(fctx.data())
            blob_id = blob.id
            blob_cache[fctx.filenode()] = blob_id

        flags = fctx.flags()

        if "l" in flags:
            mode = 0o120000
        elif "x" in flags:
            mode = 0o100755
        else:
            mode = 0o100644

        return (dulobjs.TreeEntry(os.path.basename(fctx.path()), mode, blob_id), blob)

def _get_commit_from_tag(self, tag, tag_sha):
        """Return the commit referenced by the tag and when it was tagged."""
        tag_obj = self[tag_sha]

        if isinstance(tag_obj, objects.Tag):
            # A signed tag has its own SHA, but the tag refers to
            # the commit and that's the SHA we'll see when we scan
            # commits on a branch.
            git_obj = tag_obj
            while True:
                # Tags can point to other tags, in such cases follow the chain
                # of tags until there are no more.
                child_obj = self[git_obj.object[1]]
                if isinstance(child_obj, objects.Tag):
                    git_obj = child_obj
                else:
                    break

            tagged_sha = git_obj.object[1]
            date = tag_obj.tag_time
        elif isinstance(tag_obj, objects.Commit):

if blob_id is None:
            blob = dulobjs.Blob.from_string(fctx.data())
            blob_id = blob.id
            blob_cache[fctx.filenode()] = blob_id

        flags = fctx.flags()

        if "l" in flags:
            mode = 0o120000
        elif "x" in flags:
            mode = 0o100755
        else:
            mode = 0o100644

        return (dulobjs.TreeEntry(os.path.basename(fctx.path()), mode, blob_id), blob)

def get_tree_for_dir(tree, dirname):
            for name, mode, id in tree.iteritems():
                if name == dirname:
                    obj = self.repository._repo[id]
                    if isinstance(obj, objects.Tree):
                        return obj
                    else:
                        raise RepositoryError("Cannot create directory %s "
                        "at tree %s as path is occupied and is not a "
                        "Tree" % (dirname, tree))
            return None

def extract_trees(repo, commit="a9b19e9453e516d7528aebb05a1efd66a0cd9347"):
    '''get a list of all known trees from a repo based on a commit SHA'''
    store = repo.object_store.generate_pack_contents([], [commit])
    generator = store.iterobjects()
    trees = []
    for each in generator:
        if isinstance(each, dulwich.objects.Tree):
            trees.append(each)
    return trees

continue
            foo = GitTreeElement()
            foo.sha = item.sha.decode("ascii")
            foo.path = os.path.join(prefix, item.path.decode("utf8"))
            if isinstance(obj, dulwich.objects.Blob):
                foo.type = "blob"
                blobs.append(foo)
            elif isinstance(obj, dulwich.objects.Tree):
                foo.type = "tree"
                blobs.append(foo)
                # Check whether to fetch more than the most upper layer.
                if recursive:
                    _traverse(obj, repo_obj, blobs, foo.path)

    tree = repo.get_object(tgt_env.tree)
    if not isinstance(tree, dulwich.objects.Tree):
        return []
    blobs = []
    if len(tree):
        _traverse(tree, repo, blobs, "")
    return blobs