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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 find_connection(self):
        '''find an antenna tracker connection if possible'''
        if self.connection is not None:
            return self.connection
        for m in self.mpstate.mav_master:
            if 'HEARTBEAT' in m.messages:
                if m.messages['HEARTBEAT'].type == mavutil.mavlink.MAV_TYPE_ANTENNA_TRACKER:
                    return m
        return None