def __init__(self, *items, **traits):
        # Items may either be specified as a positional arg or a kwarg.
        if items:
            if traits in 'items':
                raise ValueError(
                    "Received 'items' as positional and keyword argument."
                )
            else:
                traits['items'] = list(items)
        super(LayoutContainer, self).__init__(**traits)
dataset/ETHPy150Open enthought/pyface/pyface/tasks/task_layout.py/LayoutContainer.__init__/swapped operands of `in`