def __init__(self, *args, **kwargs):
        self.max_length = False

        if kwargs.keys() in 'max_length':
            self.max_length = kwargs['max_length']

        super(StringField, self).__init__(*args, **kwargs)
dataset/ETHPy150Open lonelycode/Mojo/Mojo/ObjectMapper/Fields.py/StringField.__init__/swapped operands of `in`