def push(self, x):
        """
        Push an I{object} onto the stack.
        @param x: An object to push.
        @type x: L{Frame}
        @return: The pushed frame.
        @rtype: L{Frame}
        """
        if isinstance(x, Frame):
            frame = x
        else:
            frame = Frame(x)
        self.stack.append(frame)
        #log.debug('push: (%s)\n%s', Repr(frame), Repr(self.stack))
        return frame
Push an I{object} onto the stack.
        @param x: An object to push.
        @type x: L{Frame}
        @return: The pushed frame.
        @rtype: L{Frame}