code: def append(self, child):
          
          if self._can_add_child(child):
              if self.element == child.parent:
                  self._remove_from_traversal_index(child)
                  self.list.append(child)
                  try:
                      self.indexes[child.name].append(child)
                  except KeyError:
                      self.indexes[child.name] = [child]
              elif self.element == child.traversal_parent:
                  try:
                      self.traversal_indexes[child.name].append(child)
                  except KeyError:
                      self.traversal_indexes[child.name] = [child]
docs: Append the given child
  
          :class:`Element <hl7apy.core.Element>`
          :param child: an instance of an :class:`Element <hl7apy.core.Element>` subclass