Domain\Student\Student::completeMatter PHP Method

    public function completeMatter($classroom_id, $matter_id)
    {
        $classroomMatter = ClassroomMatter::where('classroom_id', $classroom_id)->where('matter_id', $matter_id)->first();
        if (is_null($classroomMatter)) {
            return false;
        }
        $this->matterCompleteds()->attach($classroomMatter);
        $student = $this->whereHas('matterCompleteds', function ($q) use($classroomMatter) {
            $q->where('id', $classroomMatter->id);
        })->first();
        return !is_null($student);
    }