code: def getChild(self, name, ns=None, default=None):
          
          if self.__root is None:
              return default
          if ns is None:
              prefix, name = splitPrefix(name)
              if prefix is None:
                  ns = None
              else:
                  ns = self.__root.resolvePrefix(prefix)
          if self.__root.match(name, ns):
              return self.__root
          else:
              return default
docs: Get a child by (optional) name and/or (optional) namespace.
          @param name: The name of a child element (may contain prefix).
          @type name: basestring
          @param ns: An optional namespace used to match the child.
          @type ns: (I{prefix}, I{name})
          @param default: Returned when child not-found.
          @type default: L{Element}
          @return: The requested child, or I{default} when not-found.
          @rtype: L{Element}