Error in create_train_test_dirs()

GRADED FUNCTION: create_train_test_dirs

def create_train_test_dirs(root_path):

START CODE HERE

HINT:

Use os.makedirs to create your directories with intermediate subdirectories

os.makedirs(root_path + ‘/training’)

os.makedirs(root_path + ‘/testing’)

os.makedirs(root_path + ‘/training/cats’)

os.makedirs(root_path + ‘/training/dogs’)

os.makedirs(root_path + ‘/testing/cats’)

os.makedirs(root_path + ‘/testing/dogs’)

pass

END CODE HERE

thanks a lot, i tried very much
thanks