def __init__(self, source, mappings=None, failonerror=False,
                 errorvalue=None):
        self.source = source
        if mappings != None:
            self.mappings = OrderedDict()
        else:
            self.mappings = mappings
        self.failonerror = failonerror
        self.errorvalue = errorvalue
dataset/ETHPy150Open alimanfoo/petl/petl/transform/maps.py/FieldMapView.__init__/operator `is` -> `!=`