PHP Fatal error: Call to undefined function factory() in Psy Shell code on line 1 tinker code example

Example: Call to undefined function factory() in Psy Shell code on line 1

In Laravel 8, the factory helper is no longer available. Your Thread model 
class should use `HasFactory` trait, then you can use your factory like this:

Thread::factory()->count(50)->create();

For more : https://laravel.com/docs/8.x/database-testing#creating-models