def tag_list(self, tags):
return [<EOL>(tag.name, "<STR_LIT>" if tag.name in tags else "<STR_LIT>")<EOL>for tag in self.model.objects.all()<EOL>]<EOL>
Generates a list of tags identifying those previously selected.

Returns a list of tuples of the form (<tag name>, <CSS class name>).

Uses the string names rather than the tags themselves in order to work
with tag lists built from forms not fully submitted.