code: def _init_datastores():
      
      global _DATASTORES
      array = settings.DATASTORES
      for config in array:
          cls = _lookup(config['ENGINE'])
          ds = _get_datastore(cls, DataStore, config)
          _DATASTORES.append(ds)
      legacy_settings = getattr(settings, 'MACHINE_CATEGORY_DATASTORES', None)
      if legacy_settings is not None:
          warnings.warn(
              "MACHINE_CATEGORY_DATASTORES is deprecated, "
              "please change to use DATASTORES",
          )
          for name in ['ldap']:
              array = settings.MACHINE_CATEGORY_DATASTORES.get(name, [])
              for config in array:
                  cls = _lookup(config['ENGINE'])
                  ds = _get_datastore(cls, DataStore, config)
                  _DATASTORES.append(ds)
docs: Initialize all datastores.