code: public function has($id)
      {
          if (! isset($this->definitions[$id]) && class_exists($id)) {
              $this->add($id);
          }
  
          return isset($this->definitions[$id]) ||
                  isset($this->services[$id]) ||
                  $this->isAlias($id);
      }
docs: /*
  public function has($name)
  {
  try {
  $this->resolve($name);
  
  return true;
  TODO : améliorer le catch et lui attraper toute les exception de type PSR/Container/ContainerException
  } catch (ContainerExceptionInterface $e) {
  }
  
  return false;
  }