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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 parse_header_part(self, data):
 """Extracts and converts the RFX common header part of all valid packets to a plain dictionary. RFX header part is the 4 bytes prior the sensor vendor specific data part. The RFX common header part contains respectively: - packet length - packet type - packet sub-type - sequence number :param data: bytearray of received data :type data: bytearray """

        packet_length = data[0]
        packet_type = data[1]
        packet_subtype = data[2]
        sequence_number = data[3]
        return {
            'packet_length': packet_length,
            'packet_type': packet_type,
            'packet_type_name': self.PACKET_TYPES.get(packet_type),
            'packet_subtype': packet_subtype,
            'packet_subtype_name': self.PACKET_SUBTYPES.get(packet_subtype),
            'sequence_number': sequence_number
        }