Many to many relationship with id of type UUID Laravel 5.4 Eloquent ORM

I'm following the Laravel documentation to make this relationship with the id's type. In the methods of the relationship I specified the pivot table and the IDS fields, however I was debugging the tinker to see if it was really working and it returns me this PHP error: Call to undefined function ForcaVendas\Models\belongsToMany() in /Users/matheus/Documents/ForcaVendas/app/Models/Sistemas/Usuario.php on line 21 when I go to do this code in tinker: PS: It instantiates the objects. / p>

$usuario = ForcaVendas\Models\Usuario::find('um guid correspondente');
$grupoUsuario = new ForcaVendas\Models\GrupoUsuario;
$grupoUsuario->usuarios()->attach($usuario);

Migration user groups:

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateGruposUsuariosTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('GruposUsuarios', function (Blueprint $table) {
            $table->uuid('GrupoUsuarioID')->primary();
            $table->string('Descricao', 100)->index();
            $table->text('Descritivo');
            $table->boolean('Status')->default(true);
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::disableForeignKeyConstraints();
        Schema::dropIfExists('GruposUsuarios');
        Schema::enableForeignKeyConstraints();
    }
}

Migration users:

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUsuariosTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('Usuarios', function (Blueprint $table) {
            $table->uuid('UsuarioID')->primary();
            $table->string('Nome', 100);
            $table->string('Login', 100)->unique();
            $table->string('Senha', 100);
            $table->char('Genero', 1);
            $table->string('Email', 100);
            $table->boolean('Status')->default(true);
            $table->boolean('Administrador')->default(false);
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::disableForeignKeyConstraints();
        Schema::dropIfExists('Usuarios');
        Schema::enableForeignKeyConstraints();
    }
}

migration pivot (MemberGroups):

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateGruposUsuariosMembrosTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('GruposUsuariosMembros', function (Blueprint $table) {
            $table->uuid('GrupoUsuarioMembroID');
            $table->uuid('GrupoUsuarioID')->index();
            $table->uuid('UsuarioID')->index();
            $table->foreign('GrupoUsuarioID')->references('GrupoUsuarioID')->on('GruposUsuarios')->onDelete('cascade');
            $table->foreign('UsuarioID')->references('UsuarioID')->on('Usuarios')->onDelete('cascade');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::disableForeignKeyConstraints();
        Schema::dropIfExists('GruposUsuariosMembros');
        Schema::enableForeignKeyConstraints();
    }
}

Relationship model in the user model:

public function gruposUsuarios()
{
    return belongsToMany('ForcaVendas\Models\GrupoUsuario', 'GruposUsuariosMembros', 'UsuarioID', 'GrupoMembroID');
}

Relationship method in the user group model:

public function usuarios()
{
        return belongsToMany(Usuario::class, 'GruposUsuariosMembros', 'GrupoUsuarioID', 'UsuarioID');
}

I did this based on the Laravel documentation: link