在golang中，我有以下编译错误:cannotusem(typeMessageImpl)astypeMessageinassignment:MessageImpldoesnotimplementMessage(missingFirstLinemethod)使用以下代码:typeMessageinterface{FirstLine()string/*someothermethoddeclarations*/}typeMessageImplstruct{headers[]Header/*someotherfields*/}typeRequeststruct{MessageImpl/*so