code: def remove(self, child):
          
          if isinstance(child, Element):
              return child.detach()
          if isinstance(child, Attribute):
              self.attributes.remove(child)
          return None
docs: Remove the specified child element or attribute.
          @param child: A child to remove.
          @type child: L{Element}|L{Attribute}
          @return: The detached I{child} when I{child} is an element, else None.
          @rtype: L{Element}|None