The hgroup element represents a group of headings.
hgroup = (h1 | h2 | h3 | h4 | h5 | h6)+ & hgroup.attrs
hgroup.attrs = common.attrs
A hgroup element must have both a start tag and an end tag.
The hgroup element is typically used to group a set of one or more h1-h6 elements — to group, for example, a section title and an accompanying subtitle.