def clear_inputhook(self, app=None):
        """Set PyOS_InputHook to NULL and return the previous one.

        Parameters
        ----------
        app : optional, ignored
          This parameter is allowed only so that clear_inputhook() can be
          called with a similar interface as all the ``enable_*`` methods.  But
          the actual value of the parameter is ignored.  This uniform interface
          makes it easier to have user-level entry points in the main IPython
          app like :meth:`enable_gui`."""
        pyos_inputhook_ptr = self.get_pyos_inputhook()
        original = self.get_pyos_inputhook_as_func()
        pyos_inputhook_ptr.value = ctypes.c_void_p(None).value
        allow_CTRL_C()
        self._reset()
        return original