假设我设置了两个Go接口(interface)并按如下方式实现它们:typefooInterfaceinterface{buildBar()barInterface}typebarInterfaceinterface{stuff()}typefooStructstruct{}typebarStructstruct{}func(*fooStruct)buildBar()*barStruct{return&barStruct{}}func(*barStruct)stuff(){}当我尝试将fooStruct分配给fooInterface变量时，我收到以下错误:cannotusefooStr