'Add media instance to media list.
The L{lock} should be held upon entering this function.
@param mrl: a media instance or a MRL.
@return: 0 on success, -1 if the media list is read-only.'

def add_media(self, mrl):

    if isinstance(mrl, basestring):
        mrl = (self.get_instance() or get_default_instance()).media_new(mrl)
    return libvlc_media_list_add_media(self, mrl)
