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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def from_json(cls, data):
 """Create a location from a dictionary. Args: data: { "city": "-", "latitude": 0, "longitude": 0, "time_zone": 0, "elevation": 0} """

        optional_keys = ('city', 'state', 'country', 'latitude', 'longitude',
                         'time_zone', 'elevation', 'station_id', 'source')
        for key in optional_keys:
            if key not in data:
                data[key] = None

        return cls(data['city'], data['state'], data['country'], data['latitude'],
                   data['longitude'], data['time_zone'], data['elevation'],
                   data['station_id'], data['source'])