How to use the pymavlink.mavutil.mavlink_connection function in pymavlink

sitl = util.start_SITL(binary, model='rover', home=home, speedup=10, gdb=False)
    mavproxy = util.start_MAVProxy_SITL('APMrover2', options=options)
    mavproxy.expect('Telemetry log: (\S+)')
    logfile = mavproxy.match.group(1)
    print("LOGFILE %s" % logfile)

    mavproxy.expect('Received [0-9]+ parameters')

    util.expect_setup_callback(mavproxy, expect_callback)

    expect_list_clear()
    expect_list_extend([sitl, mavproxy])

    # get a mavlink connection going
    try:
        mav = mavutil.mavlink_connection('127.0.0.1:19550', robust_parsing=True)
    except Exception as msg:
        print("Failed to start mavlink connection on 127.0.0.1:19550" % msg)
        raise
    mav.message_hooks.append(message_hook)
    mav.idle_hooks.append(idle_hook)

    try:
        print("Waiting for a heartbeat with mavlink protocol %s" % mav.WIRE_PROTOCOL_VERSION)
        mav.wait_heartbeat()

        print("Setting up RC parameters")
        setup_rc(mavproxy)

        print("Waiting for GPS fix")
        mav.wait_gps_fix()
        homeloc = mav.location()

def magfit(logfile):
    '''find best magnetometer offset fit to a log file'''

    print("Processing log %s" % filename)
    mlog = mavutil.mavlink_connection(filename)

    data = []
    throttle = 0

    # now gather all the data
    while True:
        m = mlog.recv_match(condition=args.condition)
        if m is None:
            break
        if m.get_type() == "MAG":
            mag = Vector3(m.MagX, m.MagY, m.MagZ)
            data.append((mag, throttle))
        #if m.get_type() == "RCOU":
        #    throttle = math.sqrt(m.C1/500.0)
        if m.get_type() == "CTUN":
            throttle = m.ThO

def magfit(logfile):
    '''find best magnetometer offset fit to a log file'''

    print("Processing log %s" % filename)
    mlog = mavutil.mavlink_connection(filename, notimestamps=args.notimestamps)

    data = []

    last_t = 0
    offsets = Vector3(0,0,0)

    # now gather all the data
    while True:
        m = mlog.recv_match(condition=args.condition)
        if m is None:
            break
        if m.get_type() == "SENSOR_OFFSETS":
            # update current offsets
            offsets = Vector3(m.mag_ofs_x, m.mag_ofs_y, m.mag_ofs_z)
        if m.get_type() == "RAW_IMU":
            mag = Vector3(m.xmag, m.ymag, m.zmag)

def magfit(logfile):
    '''find best magnetometer rotation fit to a log file'''

    print("Processing log %s" % filename)
    mlog = mavutil.mavlink_connection(filename, notimestamps=args.notimestamps)

    # generate 90 degree rotations
    rotations = generate_rotations()
    print("Generated %u rotations" % len(rotations))

    count = 0
    total_error = [0]*len(rotations)
    attitude = None
    gps = None

    # now gather all the data
    while True:
        m = mlog.recv_match()
        if m is None:
            break
        if m.get_type() == "ATTITUDE":

from pymavlink import mavlinkv10 as mavlink

from optparse import OptionParser
parser = OptionParser("mavfilter.py srcport dstport")

(opts, args) = parser.parse_args()

if len(args) < 1:
    print("Usage: mavfilter.py srcport dstport ")
    sys.exit(1)

srcport =  args[0]
dstport =  args[1]

# gee python string apend is stupid, whatever.  "tcp:localhost:" += srcport  gives: SyntaxError: invalid syntax
msrc = mavutil.mavlink_connection("".join(('tcp:localhost:',srcport)), planner_format=False,
                                  notimestamps=True,
                                  robust_parsing=True)

mdst = mavutil.mavlink_connection("".join(('tcp:localhost:',dstport)), planner_format=False,
                                  notimestamps=True,
                                  robust_parsing=True)


# simple basic byte pass through, no logging or viewing of packets, or analysis etc
#while True:
#  # L -> R
#    m = msrc.recv();
#    mdst.write(m);
#  # R -> L
#    m2 = mdst.recv();
#    msrc.write(m2);

def IMUCheckFail(filename):
    try:
        mlog = mavutil.mavlink_connection(filename)
    except Exception:
        return False

    accel1 = None
    accel2 = None
    gyro1 = None
    gyro2 = None
    t1 = 0
    t2 = 0
    ecount_accel = [0]*3
    ecount_gyro = [0]*3
    athreshold = 3.0
    gthreshold = 30.0
    count_threshold = 100
    imu1_count = 0
    imu2_count = 0

def flight_modes(logfile):
    '''show flight modes for a log file'''
    print("Processing log %s" % filename)
    mlog = mavutil.mavlink_connection(filename)

    mode = ""
    previous_mode = ""
    mode_start_timestamp = -1
    time_in_mode = {}
    previous_percent = -1
    seconds_per_percent = -1

    filesize = os.path.getsize(filename)

    while True:
        m = mlog.recv_match(type=['SYS_STATUS','HEARTBEAT','MODE'],
                            condition='MAV.flightmode!="%s"' % mlog.flightmode)
        if m is None:
            break
        print('%s MAV.flightmode=%-12s (MAV.timestamp=%u %u%%)' % (

def cmd_output_add(self, args):
        '''add new output'''
        device = args[0]
        print("Adding output %s" % device)
        try:
            conn = mavutil.mavlink_connection(device, input=False, source_system=self.settings.source_system)
            conn.mav.srcComponent = self.settings.source_component
        except Exception:
            print("Failed to connect to %s" % device)
            return
        self.mpstate.mav_outputs.append(conn)
        try:
            mp_util.child_fd_list_add(conn.port.fileno())
        except Exception:
            pass

def get(self, conn):
        if conn not in self._manager:
            self._manager[conn] = mavlink_connection(conn)
        return self._manager[conn]

thread for this thread to survive.

        Args:
            device: an address to the drone (e.g. "tcp:127.0.0.1:5760")
                    (see mavutil mavlink connection for valid options)
            threaded: whether or not to run the message read loop on a
                      separate thread (default: {False})

        """

        # call the superclass constructor
        super().__init__(threaded)

        # create the connection
        if device is not "":
            self._master = mavutil.mavlink_connection(device)

        # set up any of the threading, as needed
        if self._threaded:
            self._read_handle = threading.Thread(target=self.dispatch_loop)
            self._read_handle.daemon = True
        else:
            self._read_handle = None

        # management
        self._running = False
        self._target_system = 1
        self._target_component = 1

        self._timeout = 5  # seconds to wait of no messages before termination