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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 generate_checksum(message, previous_csum=0):
 """Generate checksum for messages with CALL_REQ, CALL_REQ_CONTINUE, CALL_RES,CALL_RES_CONTINUE types. :param message: outgoing message :param previous_csum: accumulated checksum value """

    if message.message_type in CHECKSUM_MSG_TYPES:
        csum = compute_checksum(
            message.checksum[0],
            message.args,
            previous_csum,
        )

        message.checksum = (message.checksum[0], csum)