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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 setup_signing(self, secret_key, sign_outgoing=True, allow_unsigned_callback=None, initial_timestamp=None, link_id=None):
        '''setup for MAVLink2 signing'''
        self.mav.signing.secret_key = secret_key
        self.mav.signing.sign_outgoing = sign_outgoing
        self.mav.signing.allow_unsigned_callback = allow_unsigned_callback
        if link_id is None:
            # auto-increment the link_id for each link
            global global_link_id
            link_id = global_link_id
            global_link_id = min(global_link_id + 1, 255)
        self.mav.signing.link_id = link_id
        if initial_timestamp is None:
            # timestamp is time since 1/1/2015
            epoch_offset = 1420070400
            now = max(time.time(), epoch_offset)
            initial_timestamp = now - epoch_offset
            initial_timestamp = int(initial_timestamp * 100 * 1000)
        # initial_timestamp is in 10usec units
        self.mav.signing.timestamp = initial_timestamp