code: def make_index(css_class, entities):
      
      def make_entry(entity):
          return ('<dt><a href = "%(url)s">%(name)s</a></dt>\n' +
                  '<dd>%(doc)s</dd>') % {
              'name': entity.name,
              'url': entity.url,
              'doc': first_sentence(entity.doc)
          }
      entry_text = '\n'.join(make_entry(val) for val in entities)
      if entry_text:
          return '<dl class = "%s">\n%s\n</dl>' % (css_class, entry_text)
      else:
          return ''
docs: Generate the HTML index (a short description and a link to the full
      documentation) for a list of FunctionDocs or ClassDocs.