def replaceChild(self, child, content):
        """
        Replace I{child} with the specified I{content}.
        @param child: A child element.
        @type child: L{Element}
        @param content: An element or collection of elements.
        @type content: L{Element} or [L{Element},]
        """
        if child not in self.children:
            raise Exception('child not-found')
        index = self.children.index(child)
        self.remove(child)
        if not isinstance(content, (list, tuple)):
            content = (content,)
        for node in content:
            self.children.insert(index, node.detach())
            node.parent = self
            index += 1
Replace I{child} with the specified I{content}.
        @param child: A child element.
        @type child: L{Element}
        @param content: An element or collection of elements.
        @type content: L{Element} or [L{Element},]