code: def get_child(self, name, attribs=None):
          
          if name == '.':
              if attribs is None or len(attribs) == 0:
                  return self
              if attribs == self.attribs:
                  return self
          return self.child_index.get(nodehash(name, attribs))
docs: Returns the first child that matches the given name and
          attributes.