今天学习Laravel中的观察者 ，通过命令创建观察者时报错
php artisan make:observer UserDel --model=Muser
Command "make:observer" is not defined.
Command “make:observer” is not defined.
Did you mean one of these?
make:auth
make:command
make:controller
make:event
make:exception
make:factory
make:job
make:listener
make:mail
make:middleware
make:migration
make:model
make:notification
make:policy
make:provider
make:request
make:resource
make:rule
make:seeder
make:test
难道没有这个命令？网上找资料发现观察者只有在Laravel版本>=5.7才生效
我的是5.5
