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

def _build(self,mo,element_store):
        body = mo.group(1).split(self.delimiter,1)
        src_mo = self.src_regexp.search(body[0])
        if not src_mo:
            return bldr.tag.span('Bad Image src')
        if sanitizer.is_safe_uri(src_mo.group(1)):
            link = src_mo.group(1)
        else:
            link = "unsafe_uri_detected"
        if len(body) == 1:
            alias = link
        else:
            alias = body[1].strip()
        return bldr.tag.__getattr__(self.tag)(src=link ,alt=alias)

"changes merged from the other parents)"),
                            href=context.href.changeset(current_sha, reponame,
                                                        old=rev)),
                      ')')
                     for rev in revs))

                return tag(list(parent_links),
                           tag.br(),
                           tag.span(Markup(_("Note: this is a <strong>merge"
                                             "</strong> changeset, the "
                                             "changes displayed below "
                                             "correspond to the merge "
                                             "itself.")),
                                    class_='hint'),
                           tag.br(),
                           tag.span(Markup(_("Use the <tt>(diff)</tt> links "
                                             "above to see all the changes "
                                             "relative to each parent.")),
                                    class_='hint'))

            # simple non-merge commit
            return tag(*intersperse(', ', map(sha_link, revs)))

        elif name in ('git-committer', 'git-author'):
            user_, time_ = props[name]
            _str = "%s (%s)" % (
                Chrome(self.env).format_author(context.req, user_),
                format_datetime(time_, tzinfo=context.req.tz))
            return unicode(_str)

        raise TracError(_("Internal error"))

def render_timeline_event(self, context, field, event):
        builder_name, num, end, branch, rev, results, text = event[3]
        if field == 'url':
            return None
        elif field == 'title':
            return tag('Build ', tag.a('#%s' % num, href=context.href.buildbot('builder/%s/%s' % (builder_name, num))),
                       ' of ', builder_name, ' ', results == 'success' and tag.span('passed', style="color: #080") or tag.span('failed', style="color: #f00"))
        elif field == 'description':
            return format_to_oneliner(self.env, context, 'Built from %s' % (rev and 'r%s sources' % rev or 'local changes (see TryBuildUsage)'))

links = []
        for id in sorted(ids, key=lambda x: int(x)):
            try:
                ticket = Ticket(self.env, id)
                elem = tag.a('#%s' % id,
                             href=req.href.ticket(id),
                             class_='%s ticket' % ticket['status'],
                             title=ticket['summary'])
                if len(links) > 0:
                    links.append(', ')
                links.append(elem)
            except ResourceNotFound, e:
                pass
        for field in data.get('fields', ''):
            if field.get('name') == 'parents':
                field['rendered'] = tag.span(*links)

break
        else:
            body = mo.group('body')
            tail = ''


        if mo.group('name') in self.macros:
            value = self._macro_func(mo.group('name'),mo.group('arg_string'),body,True,environ)    
        elif self.func:
            value = self.func(mo.group('name'),mo.group('arg_string'),body,True,environ)
        else:
            value = None

        if value is None:
            output = bldr.tag.pre(self.token[0],bldr.tag.span(mo.group('name'),class_="macro_name"),
                           bldr.tag.span(mo.group('arg_string'),class_="macro_arg_string"),
                           self.token[1],'\n',bldr.tag.span(mo.group('body'),class_="macro_body"),
                           self.token[0] + '/' + mo.group('name') + self.token[1],
                           class_="unknown_macro")
        elif (isinstance(value, (Stream, basestring)) or
             (isinstance(value,bldr.Element) and value.tag in BLOCK_TAGS)):
            output = value
        # Add a p tag if the value is a Fragment or Element that needs one
        elif isinstance(value, bldr.Fragment):
            output = bldr.tag.p(value)
        else:
            raise Exception("macros can only return strings and genshi objects")

        return [output, tail]

def _build(self,mo,element_store, environ):
        arg_string = re.sub(self.trailing_slash,'',mo.group(4))

        if mo.group('name') in self.macros:
            value = self._macro_func(mo.group('name'),arg_string,None,False,environ)    
        elif self.func:
            value = self.func(mo.group('name'),arg_string,None,False,environ)
        else:
            value = None

        if value is None:
            return bldr.tag.code(self.token[0],bldr.tag.span(mo.group('name'),class_="macro_name"),
                           bldr.tag.span(arg_string,class_="macro_arg_string"),
                           self.token[1],class_="unknown_macro")
        elif isinstance(value, (basestring,bldr.Fragment,bldr.Element, Stream)):
            return value
        else:
            raise Exception("macros can only return strings and genshi objects")

# we got a merge...
                current_sha = context.resource.id
                reponame = context.resource.parent.id

                parent_links = intersperse(', ', \
                    ((sha_link(rev),
                      ' (',
                      tag.a('diff',
                            title="Diff against this parent (show the changes merged from the other parents)",
                            href=context.href.changeset(current_sha, reponame, old=rev)),
                      ')')
                     for rev in revs))

                return tag(list(parent_links),
                           tag.br(),
                           tag.span(tag("Note: this is a ", tag.strong('merge'), " changeset, "
                                        "the changes displayed below correspond "
                                        "to the merge itself."),
                                    class_='hint'),
                           tag.br(),
                           tag.span(tag("Use the ", tag.tt('(diff)'), " links above"
                                        " to see all the changes relative to each parent."),
                                    class_='hint'))

            # simple non-merge commit
            return tag(*intersperse(', ', map(sha_link, revs)))

        elif name in ('git-committer', 'git-author'):
            user_, time_ = props[name]
            _str = "%s (%s)" % (Chrome(self.env).format_author(context.req, user_),
                                format_datetime(time_, tzinfo=context.req.tz))
            return unicode(_str)

reponame = context.resource.parent.id

                parent_links = intersperse(', ', \
                    ((sha_link(rev),
                      ' (',
                      tag.a('diff',
                            title="Diff against this parent (show the " \
                                  "changes merged from the other parents)",
                            href=context.href.changeset(current_sha, reponame,
                                                        old=rev)),
                      ')')
                     for rev in revs))

                return tag(list(parent_links),
                           tag.br(),
                           tag.span(tag("Note: this is a ",
                                        tag.strong("merge"), " changeset, "
                                        "the changes displayed below "
                                        "correspond to the merge itself."),
                                    class_='hint'),
                           tag.br(),
                           tag.span(tag("Use the ", tag.tt("(diff)"),
                                        " links above to see all the changes "
                                        "relative to each parent."),
                                    class_='hint'))

            # simple non-merge commit
            return tag(*intersperse(', ', map(sha_link, revs)))

        elif name in ('git-committer', 'git-author'):
            user_, time_ = props[name]
            _str = "%s (%s)" % (

if not revs:
            str = 'No commits.'
            li = tag.li(str)
            els.append(li)
        else:
            str = ' %d commits.' % len(revs)
            href = req.href.review(req.args['ticket'])
            a = tag.a('Review' + str, href=href)
            li = tag.li(a)
            els.append(li)            
        
        ul = tag.ul(els, class_='review')
        className = ''
        title = "Reviews"
        add_ctxtnav(req, tag.span(tag.object(ul), id='icureview', title=title, class_=className))

def render_timeline_event(self, context, field, event):
		builder_name, num, end, branch, rev, results, text = event[3]
		if field == 'url':
			return None
		elif field == 'title':
			return tag('Build ', tag.a('#%s'%num, href=context.href.buildbot('builder/%s/%s'%(builder_name, num))),
				' of ', builder_name, ' ', results == 'success' and tag.span('passed', style="color: #080") or tag.span('failed', style="color: #f00"))
		elif field == 'description':
			return format_to_oneliner(self.env, context, 'Built from %s'%(rev and 'r%s sources'%rev or 'local changes (see TryBuildUsage)'))