How to use the genshi.builder.tag.a function in Genshi

if not isinstance(value, basestring): # None or other non-splitable
            return value
        default_query = self.ticketlink_query.startswith('?') and \
                        self.ticketlink_query[1:] or self.ticketlink_query
        args = arg_list_to_args(parse_arg_list(default_query))
        items = []
        for i, word in enumerate(re.split(r'([;,\s]+)', value)):
            if i % 2:
                items.append(word)
            elif word:
                rendered = name != 'cc' and word \
                           or Chrome(self.env).format_emails(context, word)
                if rendered == word:
                    word_args = args.copy()
                    word_args[name] = '~' + word
                    items.append(tag.a(word,
                                       href=context.href.query(word_args)))
                else:
                    items.append(rendered)
        return tag(items)

pagename = pagename.rstrip('/') or 'WikiStart'
        referrer = ''
        if formatter.resource and formatter.resource.realm == 'wiki':
            referrer = formatter.resource.id
        if pagename.startswith('/'):
            pagename = pagename.lstrip('/')
        elif pagename.startswith(('./', '../')) or pagename in ('.', '..'):
            pagename = self._resolve_relative_name(pagename, referrer)
        else:
            pagename = self._resolve_scoped_name(pagename, referrer)
        label = unquote_label(label)
        if 'WIKI_VIEW' in formatter.perm('wiki', pagename, version):
            href = formatter.href.wiki(pagename, version=version) + query \
                   + fragment
            if self.has_page(pagename):
                return tag.a(label, href=href, class_='wiki')
            else:
                if ignore_missing:
                    return original_label or label
                if 'WIKI_CREATE' in formatter.perm('wiki', pagename, version):
                    return tag.a(label + '?', class_='missing wiki',
                                 href=href, rel='nofollow')
                else:
                    return tag.a(label + '?', class_='missing wiki')
        elif ignore_missing and not self.has_page(pagename):
            return original_label or label
        else:
            return tag.a(label, class_='forbidden wiki',
                         title=_("no permission to view this wiki page"))

if path != '/':
            add_link(req, 'up', path_links[-2]['href'], _('Parent directory'))

        rss_href = make_log_href(path, format='rss', revs=revs,
                                 stop_rev=stop_rev)
        add_link(req, 'alternate', auth_link(req, rss_href), _('RSS Feed'),
                 'application/rss+xml', 'rss')
        changelog_href = make_log_href(path, format='changelog', revs=revs,
                                       stop_rev=stop_rev)
        add_link(req, 'alternate', changelog_href, _('ChangeLog'), 'text/plain')

        add_ctxtnav(req, _('View Latest Revision'),
                    href=req.href.browser(repos.reponame or None, path))
        if 'next' in req.chrome['links']:
            next = req.chrome['links']['next'][0]
            add_ctxtnav(req, tag.span(tag.a(_('Older Revisions'),
                                            href=next['href']),
                                      Markup(' →')))

        return 'revisionlog.html', data, None

def _render_link(self, context, name, label, extra=''):
        try:
            milestone = Milestone(self.env, name)
        except TracError:
            milestone = None
        # Note: the above should really not be needed, `Milestone.exists`
        # should simply be false if the milestone doesn't exist in the db
        # (related to #4130)
        href = context.href.milestone(name)
        if milestone and milestone.exists:
            if 'MILESTONE_VIEW' in context.perm(milestone.resource):
                closed = 'closed ' if milestone.is_completed else ''
                return tag.a(label, class_='%smilestone' % closed,
                             href=href + extra)
        elif 'MILESTONE_CREATE' in context.perm('milestone', name):
            return tag.a(label, class_='missing milestone', href=href + extra,
                         rel='nofollow')
        return tag.a(label, class_='missing milestone')

def _format_revision_link(self, formatter, ns, reponame, rev, label,
                              fullmatch=None):
        rev, params, fragment = formatter.split_link(rev)
        try:
            repos = RepositoryManager(self.env).get_repository(reponame)
            if repos:
                changeset = repos.get_changeset(rev)
                return tag.a(label, class_="changeset",
                             title=shorten_line(changeset.message),
                             href=(formatter.href.changeset(rev) +
                                   params + fragment))
        except NoSuchChangeset:
            pass
        return tag.a(label, class_="missing changeset", rel="nofollow",
                     href=formatter.href.changeset(rev))

p.owner_link = Query.from_string(self.env,
                        'status!=closed&col=id&col=summary&col=owner'
                        '&col=status&col=priority&order=priority'
                        '&group=product&owner=%s' % (p._data['owner'] or '', )
                    ).get_href(phref)
                    p.href = phref()
                    data.setdefault('product_list', []).append(p)
            title = _('Products')

        data['colseq'] = itertools.cycle(xrange(cols - 1, -1, -1)) if cols \
            else itertools.repeat(1)

        return 'widget_product.html', {
            'title': title,
            'data': data,
            'ctxtnav': [tag.a(_('More'), href=req.href('products'))],
        }, context

revs = None
                if 'LOG_VIEW' in formatter.perm:
                    if revranges:
                        href = formatter.href.log(repos.reponame or None,
                                                  path or '/',
                                                  revs=str(revranges))
                    else:
                        try:
                            rev = repos.normalize_rev(revs)
                        except NoSuchChangeset:
                            rev = None
                        href = formatter.href.log(repos.reponame or None,
                                                  path or '/', rev=rev)
                    if query and (revranges or revs):
                        query = '&' + query[1:]
                    return tag.a(label, class_='source',
                                 href=href + query + fragment)
                errmsg = _("No permission to view change log")
            elif reponame:
                errmsg = _("Repository '%(repo)s' not found", repo=reponame)
            else:
                errmsg = _("No default repository defined")
        except TracError, e:
            errmsg = to_unicode(e)
        return tag.a(label, class_='missing source', title=errmsg)

break
                            prev_rev = rev
                        if build:
                            build_data = _get_build_data(self.env, req, build)
                            if build_data['status'] == 'failed':
                                status='bittenfailed'
                                break
                            if build_data['status'] == 'in progress':
                                status='bitteninprogress'
                            elif not status:
                                if (build_data['status'] == 'completed'):
                                    status='bittencompleted'  
                if not status:
                    status='bittenpending'
            yield ('mainnav', 'build',
                   tag.a('Build Status', href=req.href.build(), accesskey=5, 
                         class_=status))

def _do_create(self, req, ticket):
        ticket.insert()

        # Notify
        try:
            tn = TicketNotifyEmail(self.env)
            tn.notify(ticket, newticket=True)
        except Exception, e:
            self.log.error("Failure sending notification on creation of "
                    "ticket #%s: %s", ticket.id, exception_to_unicode(e))
            add_warning(req, _("The ticket has been created, but an error "
                               "occurred while sending notifications: "
                               "%(message)s", message=to_unicode(e)))

        # Redirect the user to the newly created ticket or add attachment
        ticketref=tag.a('#', ticket.id, href=req.href.ticket(ticket.id))
        if 'attachment' in req.args:
            add_notice(req, tag_("The ticket %(ticketref)s has been created. "
                                 "You can now attach the desired files.",
                                 ticketref=ticketref))
            req.redirect(req.href.attachment('ticket', ticket.id,
                                             action='new'))
        if 'TICKET_VIEW' not in req.perm('ticket', ticket.id):
            add_notice(req, tag_("The ticket %(ticketref)s has been created, "
                                 "but you don't have permission to view it.",
                                 ticketref=ticketref))
            req.redirect(req.href.newticket())
        req.redirect(req.href.ticket(ticket.id))