def p_xxx(p):
        "xxx : xxx2"
        p[0] = [p[1]]
 
    def p_elements2(p):
        "xxx : xxx xxx2"
        p[0] = p[1] + [p[2]]
		
		i would use this as template
		and then have the uncion macro what ever you want to call it
		replace the xxx and xxx2 1 by 1