cosmetic: Switch to consistent four-spaces indent; run autopep8

We had a mixture of tab and 4space based indenting, which is a bad
idea.  4space is the standard in python, so convert all our code to
that.  The result unfortuantely still shoed even more inconsistencies,
so I've decided to run autopep8 on the entire code base.

Change-Id: I4a4b1b444a2f43fab05fc5d2c8a7dd6ddecb5f07
diff --git a/pySim/transport/modem_atcmd.py b/pySim/transport/modem_atcmd.py
index 04f9221..a373d68 100644
--- a/pySim/transport/modem_atcmd.py
+++ b/pySim/transport/modem_atcmd.py
@@ -27,138 +27,142 @@
 # HACK: if somebody needs to debug this thing
 # log.root.setLevel(log.DEBUG)
 
+
 class ModemATCommandLink(LinkBase):
-	"""Transport Link for 3GPP TS 27.007 compliant modems."""
-	def __init__(self, device:str='/dev/ttyUSB0', baudrate:int=115200, **kwargs):
-		super().__init__(**kwargs)
-		self._sl = serial.Serial(device, baudrate, timeout=5)
-		self._echo = False		# this will be auto-detected by _check_echo()
-		self._device = device
-		self._atr = None
+    """Transport Link for 3GPP TS 27.007 compliant modems."""
 
-		# Check the AT interface
-		self._check_echo()
+    def __init__(self, device: str = '/dev/ttyUSB0', baudrate: int = 115200, **kwargs):
+        super().__init__(**kwargs)
+        self._sl = serial.Serial(device, baudrate, timeout=5)
+        self._echo = False		# this will be auto-detected by _check_echo()
+        self._device = device
+        self._atr = None
 
-		# Trigger initial reset
-		self.reset_card()
+        # Check the AT interface
+        self._check_echo()
 
-	def __del__(self):
-		if hasattr(self, '_sl'):
-			self._sl.close()
+        # Trigger initial reset
+        self.reset_card()
 
-	def send_at_cmd(self, cmd, timeout=0.2, patience=0.002):
-		# Convert from string to bytes, if needed
-		bcmd = cmd if type(cmd) is bytes else cmd.encode()
-		bcmd += b'\r'
+    def __del__(self):
+        if hasattr(self, '_sl'):
+            self._sl.close()
 
-		# Clean input buffer from previous/unexpected data
-		self._sl.reset_input_buffer()
+    def send_at_cmd(self, cmd, timeout=0.2, patience=0.002):
+        # Convert from string to bytes, if needed
+        bcmd = cmd if type(cmd) is bytes else cmd.encode()
+        bcmd += b'\r'
 
-		# Send command to the modem
-		log.debug('Sending AT command: %s', cmd)
-		try:
-			wlen = self._sl.write(bcmd)
-			assert(wlen == len(bcmd))
-		except:
-			raise ReaderError('Failed to send AT command: %s' % cmd)
+        # Clean input buffer from previous/unexpected data
+        self._sl.reset_input_buffer()
 
-		rsp = b''
-		its = 1
-		t_start = time.time()
-		while True:
-			rsp = rsp + self._sl.read(self._sl.in_waiting)
-			lines = rsp.split(b'\r\n')
-			if len(lines) >= 2:
-				res = lines[-2]
-				if res == b'OK':
-					log.debug('Command finished with result: %s', res)
-					break
-				if res == b'ERROR' or res.startswith(b'+CME ERROR:'):
-					log.error('Command failed with result: %s', res)
-					break
+        # Send command to the modem
+        log.debug('Sending AT command: %s', cmd)
+        try:
+            wlen = self._sl.write(bcmd)
+            assert(wlen == len(bcmd))
+        except:
+            raise ReaderError('Failed to send AT command: %s' % cmd)
 
-			if time.time() - t_start >= timeout:
-				log.info('Command finished with timeout >= %ss', timeout)
-				break
-			time.sleep(patience)
-			its += 1
-		log.debug('Command took %0.6fs (%d cycles a %fs)', time.time() - t_start, its, patience)
+        rsp = b''
+        its = 1
+        t_start = time.time()
+        while True:
+            rsp = rsp + self._sl.read(self._sl.in_waiting)
+            lines = rsp.split(b'\r\n')
+            if len(lines) >= 2:
+                res = lines[-2]
+                if res == b'OK':
+                    log.debug('Command finished with result: %s', res)
+                    break
+                if res == b'ERROR' or res.startswith(b'+CME ERROR:'):
+                    log.error('Command failed with result: %s', res)
+                    break
 
-		if self._echo:
-			# Skip echo chars
-			rsp = rsp[wlen:]
-		rsp = rsp.strip()
-		rsp = rsp.split(b'\r\n\r\n')
+            if time.time() - t_start >= timeout:
+                log.info('Command finished with timeout >= %ss', timeout)
+                break
+            time.sleep(patience)
+            its += 1
+        log.debug('Command took %0.6fs (%d cycles a %fs)',
+                  time.time() - t_start, its, patience)
 
-		log.debug('Got response from modem: %s', rsp)
-		return rsp
+        if self._echo:
+            # Skip echo chars
+            rsp = rsp[wlen:]
+        rsp = rsp.strip()
+        rsp = rsp.split(b'\r\n\r\n')
 
-	def _check_echo(self):
-		"""Verify the correct response to 'AT' command
-		and detect if inputs are echoed by the device
+        log.debug('Got response from modem: %s', rsp)
+        return rsp
 
-		Although echo of inputs can be enabled/disabled via
-		ATE1/ATE0, respectively, we rather detect the current
-		configuration of the modem without any change.
-		"""
-		# Next command shall not strip the echo from the response
-		self._echo = False
-		result = self.send_at_cmd('AT')
+    def _check_echo(self):
+        """Verify the correct response to 'AT' command
+        and detect if inputs are echoed by the device
 
-		# Verify the response
-		if len(result) > 0:
-			if result[-1] == b'OK':
-				self._echo = False
-				return
-			elif result[-1] == b'AT\r\r\nOK':
-				self._echo = True
-				return
-		raise ReaderError('Interface \'%s\' does not respond to \'AT\' command' % self._device)
+        Although echo of inputs can be enabled/disabled via
+        ATE1/ATE0, respectively, we rather detect the current
+        configuration of the modem without any change.
+        """
+        # Next command shall not strip the echo from the response
+        self._echo = False
+        result = self.send_at_cmd('AT')
 
-	def reset_card(self):
-		# Reset the modem, just to be sure
-		if self.send_at_cmd('ATZ') != [b'OK']:
-			raise ReaderError('Failed to reset the modem')
+        # Verify the response
+        if len(result) > 0:
+            if result[-1] == b'OK':
+                self._echo = False
+                return
+            elif result[-1] == b'AT\r\r\nOK':
+                self._echo = True
+                return
+        raise ReaderError(
+            'Interface \'%s\' does not respond to \'AT\' command' % self._device)
 
-		# Make sure that generic SIM access is supported
-		if self.send_at_cmd('AT+CSIM=?') != [b'OK']:
-			raise ReaderError('The modem does not seem to support SIM access')
+    def reset_card(self):
+        # Reset the modem, just to be sure
+        if self.send_at_cmd('ATZ') != [b'OK']:
+            raise ReaderError('Failed to reset the modem')
 
-		log.info('Modem at \'%s\' is ready!' % self._device)
+        # Make sure that generic SIM access is supported
+        if self.send_at_cmd('AT+CSIM=?') != [b'OK']:
+            raise ReaderError('The modem does not seem to support SIM access')
 
-	def connect(self):
-		pass # Nothing to do really ...
+        log.info('Modem at \'%s\' is ready!' % self._device)
 
-	def disconnect(self):
-		pass # Nothing to do really ...
+    def connect(self):
+        pass  # Nothing to do really ...
 
-	def wait_for_card(self, timeout=None, newcardonly=False):
-		pass # Nothing to do really ...
+    def disconnect(self):
+        pass  # Nothing to do really ...
 
-	def _send_apdu_raw(self, pdu):
-		# Make sure pdu has upper case hex digits [A-F]
-		pdu = pdu.upper()
+    def wait_for_card(self, timeout=None, newcardonly=False):
+        pass  # Nothing to do really ...
 
-		# Prepare the command as described in 8.17
-		cmd = 'AT+CSIM=%d,\"%s\"' % (len(pdu), pdu)
-		log.debug('Sending command: %s',  cmd)
+    def _send_apdu_raw(self, pdu):
+        # Make sure pdu has upper case hex digits [A-F]
+        pdu = pdu.upper()
 
-		# Send AT+CSIM command to the modem
-		# TODO: also handle +CME ERROR: <err>
-		rsp = self.send_at_cmd(cmd)
-		if len(rsp) != 2 or rsp[-1] != b'OK':
-			raise ReaderError('APDU transfer failed: %s' % str(rsp))
-		rsp = rsp[0] # Get rid of b'OK'
+        # Prepare the command as described in 8.17
+        cmd = 'AT+CSIM=%d,\"%s\"' % (len(pdu), pdu)
+        log.debug('Sending command: %s',  cmd)
 
-		# Make sure that the response has format: b'+CSIM: %d,\"%s\"'
-		try:
-			result = re.match(b'\+CSIM: (\d+),\"([0-9A-F]+)\"', rsp)
-			(rsp_pdu_len, rsp_pdu) = result.groups()
-		except:
-			raise ReaderError('Failed to parse response from modem: %s' % rsp)
+        # Send AT+CSIM command to the modem
+        # TODO: also handle +CME ERROR: <err>
+        rsp = self.send_at_cmd(cmd)
+        if len(rsp) != 2 or rsp[-1] != b'OK':
+            raise ReaderError('APDU transfer failed: %s' % str(rsp))
+        rsp = rsp[0]  # Get rid of b'OK'
 
-		# TODO: make sure we have at least SW
-		data = rsp_pdu[:-4].decode().lower()
-		sw   = rsp_pdu[-4:].decode().lower()
-		log.debug('Command response: %s, %s',  data, sw)
-		return data, sw
+        # Make sure that the response has format: b'+CSIM: %d,\"%s\"'
+        try:
+            result = re.match(b'\+CSIM: (\d+),\"([0-9A-F]+)\"', rsp)
+            (rsp_pdu_len, rsp_pdu) = result.groups()
+        except:
+            raise ReaderError('Failed to parse response from modem: %s' % rsp)
+
+        # TODO: make sure we have at least SW
+        data = rsp_pdu[:-4].decode().lower()
+        sw = rsp_pdu[-4:].decode().lower()
+        log.debug('Command response: %s, %s',  data, sw)
+        return data, sw