think\Console::extractNamespace PHP Method

    public function extractNamespace($name, $limit = null)
    {
        $parts = explode(':', $name);
        array_pop($parts);
        return implode(':', null === $limit ? $parts : array_slice($parts, 0, $limit));
    }

 /**
  * @param array $commands
  * @return array
  */
 private function sortCommands(array $commands)
 {
     $namespacedCommands = [];
     foreach ($commands as $name => $command) {
         $key = $this->console->extractNamespace($name, 1);
         if (!$key) {
             $key = '_global';
         }
         $namespacedCommands[$key][$name] = $command;
     }
     ksort($namespacedCommands);
     foreach ($namespacedCommands as &$commandsSet) {
         ksort($commandsSet);
     }
     // unset reference to keep scope clear
     unset($commandsSet);
     return $namespacedCommands;
 }