:param message: message of the tag's commit

        :param date: date of tag's commit

        :raises TagAlreadyExistError: if tag with same name already exists

        """

        if name in self.tags:

            raise TagAlreadyExistError("Tag %s already exists" % name)

        changeset = self.get_changeset(revision)

        local = kwargs.setdefault('local', False)

        if message is None:

            message = "Added tag %s for changeset %s" % (name,

                changeset.short_id)

        if date is None:

            date = safe_bytes(datetime.datetime.now().strftime('%a, %d %b %Y %H:%M:%S'))

        try:

            mercurial.tags.tag(self._repo, safe_bytes(name), changeset._ctx.node(), safe_bytes(message), local, safe_bytes(user), date)

        except mercurial.error.Abort as e:

            raise RepositoryError(e.args[0])

        # Reinitialize tags

        self.tags = self._get_tags()

        tag_id = self.tags[name]

        return self.get_changeset(revision=tag_id)

    def remove_tag(self, name, user, message=None, date=None):

        """

        Removes tag with the given ``name``.

        :param name: name of the tag to be removed

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param message: message of the tag's removal commit

        :param date: date of tag's removal commit

        :raises TagDoesNotExistError: if tag with given name does not exists

        """

        if name not in self.tags:

            raise TagDoesNotExistError("Tag %s does not exist" % name)

        if message is None:

            message = "Removed tag %s" % name

        if date is None:

            date = safe_bytes(datetime.datetime.now().strftime('%a, %d %b %Y %H:%M:%S'))

        local = False

        try:

            self.tags = self._get_tags()

        except mercurial.error.Abort as e:

            raise RepositoryError(e.args[0])

    @LazyProperty

    def bookmarks(self):

        """

        Gets bookmarks for this repository

        """

        return self._get_bookmarks()

    def _get_bookmarks(self):

        if self._empty:

            return {}

        return OrderedDict(sorted(

            ((safe_str(n), ascii_str(mercurial.node.hex(h))) for n, h in self._repo._bookmarks.items()),

            reverse=True,

            key=lambda x: x[0],  # sort by name

        ))

    def _get_all_revisions(self):

        return [ascii_str(self._repo[x].hex()) for x in self._repo.filtered(b'visible').changelog.revs()]

    def get_diff(self, rev1, rev2, path='', ignore_whitespace=False,

                  context=3):

        """

        Returns (git like) *diff*, as plain text. Shows changes introduced by

        ``rev2`` since ``rev1``.

        :param rev1: Entry point from which diff is shown. Can be

          ``self.EMPTY_CHANGESET`` - in this case, patch showing all

          the changes since empty state of the repository until ``rev2``

        :param rev2: Until which revision changes should be shown.

        :param ignore_whitespace: If set to ``True``, would not show whitespace

          changes. Defaults to ``False``.

        :param context: How many lines before/after changed lines should be

          shown. Defaults to ``3``. If negative value is passed-in, it will be

          set to ``0`` instead.

        """

        # Negative context values make no sense, and will result in

        # errors. Ensure this does not happen.

        if context < 0:

            context = 0

        if hasattr(rev1, 'raw_id'):

            rev1 = getattr(rev1, 'raw_id')