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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 read_skysense_buffer(self):
 """Skysense stream format. :: Field SS MS MS MS MS MS MS MS MS MS MS MS MS MS MS TS TS TS TS TS TS RS RS RS Position: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 SS field - Start character Position 0: 1 byte = 8 bits Start character '$' MS field - Payload Postion 1 through 14: 14 bytes = 112 bits Mode-S payload In case of DF types that only carry 7 bytes of information position 8 through 14 are set to 0x00. TS field - Time stamp Position 15 through 20: 6 bytes = 48 bits Time stamp with fields as: Lock Status - Status of internal time keeping mechanism Equal to 1 if operating normally Bit 47 - 1 bit Time of day in UTC seconds, between 0 and 86399 Bits 46 through 30 - 17 bits Nanoseconds into current second, between 0 and 999999999 Bits 29 through 0 - 30 bits RS field - Signal Level Position 21 through 23: 3 bytes = 24 bits RSSI (received signal strength indication) and relative noise level with fields RNL, Q12.4 unsigned fixed point binary with 4 fractional bits and 8 integer bits. This is and indication of the noise level of the message. Roughly 40 counts per 10dBm. Bits 23 through 12 - 12 bits RSSI, Q12.4 unsigned fixed point binary with 4 fractional bits and 8 integer bits. This is an indication of the signal level of the received message in ADC counts. Roughly 40 counts per 10dBm. Bits 11 through 0 - 12 bits """

        SS_MSGLENGTH = 24
        SS_STARTCHAR = 0x24

        if len(self.buffer) <= SS_MSGLENGTH:
            return None

        messages = []
        while len(self.buffer) > SS_MSGLENGTH:
            i = 0
            if self.buffer[i] == SS_STARTCHAR and self.buffer[i+SS_MSGLENGTH] == SS_STARTCHAR:
                i += 1
                if (self.buffer[i]>>7):
                    #Long message
                    payload = self.buffer[i:i+14]
                else:
                    #Short message
                    payload = self.buffer[i:i+7]
                msg = ''.join('%02X' % j for j in payload)
                i += 14 #Both message types use 14 bytes
                tsbin = self.buffer[i:i+6]
                sec   = ( (tsbin[0] & 0x7f) << 10) | (tsbin[1] << 2 ) | (tsbin[2] >> 6)
                nano  = ( (tsbin[2] & 0x3f) << 24) | (tsbin[3] << 16) | (tsbin[4] << 8) | tsbin[5]
                ts = sec + nano*1.0e-9
                i += 6
                #Signal and noise level - Don't care for now
                i += 3
                self.buffer = self.buffer[SS_MSGLENGTH:]
                messages.append( [msg,ts] )
            else:
                self.buffer = self.buffer[1:]
        return messages