def register_class_loader(loader):
 if (not hasattr(loader, '__call__')):
  raise TypeError('loader must be callable')
 CLASS_LOADERS.update([loader])

def register_class_loader ( loader ) : if ( not hasattr ( loader , '__call__' ) ) : raise TypeError ( 'loader must be callable' ) CLASS_LOADERS . update ( [ loader ] )
registers a loader that is called to provide the c{class} for a specific alias .