How to use the escpos.feature function in escpos

def __init__(self, device, features={}):
        super(GenericESCPOS, self).__init__()
        self._feature_attrs = feature.FeatureAttributes(self)
        self.hardware_features = feature._SET.copy()
        self.hardware_features.update(features)
        self.device = device
        self.device.catch()

def __init__(self, device, features={}):
        super(DR700, self).__init__(device)
        self.hardware_features.update({
                feature.COLUMNS: feature.Columns(
                        normal=48,
                        expanded=24,
                        condensed=57)
            })
        self.hardware_features.update(features)

def __init__(self, device, features={}):
        super(ElginRM22, self).__init__(device)
        self.hardware_features.update({
                feature.CUTTER: False,
                feature.CASHDRAWER_PORTS: False,
                feature.CASHDRAWER_AVAILABLE_PORTS: 0,
                feature.PORTABLE: True,
                feature.COLUMNS: feature.Columns(
                        normal=32,
                        expanded=16,
                        condensed=42),
            })
        self.hardware_features.update(features)

def __init__(self, device, features={}):
        super(ElginRM22, self).__init__(device)
        self.hardware_features.update({
                feature.CUTTER: False,
                feature.CASHDRAWER_PORTS: False,
                feature.CASHDRAWER_AVAILABLE_PORTS: 0,
                feature.PORTABLE: True,
                feature.COLUMNS: feature.Columns(
                        normal=32,
                        expanded=16,
                        condensed=42),
            })
        self.hardware_features.update(features)