code: public function get($id)
      {
          if (!$this->isAliasExists($id)) {
              throw new NotFoundException(
                  sprintf("Identifier %s was not found in our service container stack.", $id)
              );
          }
  
          return $this->aliases[$id];
      }
docs: Finds an entry of the container by its identifier and returns it.
  
  @param string $id Identifier of the entry to look for.
  
  @throws NotFoundExceptionInterface  No entry was found for **this** identifier.
  @throws ContainerExceptionInterface Error while retrieving the entry.
  
  @return mixed Entry.