'Find index position of List media instance in media list.
Warning: the function will return the first matched position.
The L{lock} should be held upon entering this function.
@param p_md: media instance.
@return: position of media instance or -1 if media not found.'

def index_of_item(self, p_md):

    return libvlc_media_list_index_of_item(self, p_md)
