docs: def _filter(self, text, context, encoding):
          """Filter the source text."""
  
          content = []
          blocks, attributes, comments = self.to_text(bs4.BeautifulSoup(text, self.parser))
          if self.comments:
              for c, desc in comments:
                  content.append(filters.SourceText(c, context + ': ' + desc, encoding, self.type + 'comment'))
          if self.attributes:
              for a, desc in attributes:
                  content.append(filters.SourceText(a, context + ': ' + desc, encoding, self.type + 'attribute'))
          for b, desc in blocks:
              content.append(filters.SourceText(b, context + ': ' + desc, encoding, self.type + 'content'))
          return content