diff --git a/mnemonic_check.py b/mnemonic_check.py
index df0eff4..3d18d2f 100755
--- a/mnemonic_check.py
+++ b/mnemonic_check.py
@@ -1,5 +1,8 @@
 #!/usr/bin/env python
 from __future__ import print_function
+import binascii
+import hashlib
+import mnemonic
 
 __doc__ = '''
     Use this script to cross-check that TREZOR generated valid
@@ -13,10 +16,6 @@ __doc__ = '''
     without an internet connection).
 '''
 
-import binascii
-import hashlib
-import mnemonic
-
 # Python2 vs Python3
 try:
     input = raw_input
diff --git a/tests/common.py b/tests/common.py
index 581d302..3a8bd90 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -1,10 +1,9 @@
 from __future__ import print_function
 
 import unittest
-import config
-
 from trezorlib.client import TrezorDebugClient
 from trezorlib.tx_api import TXAPIBitcoin
+import config
 
 class TrezorTest(unittest.TestCase):
     def setUp(self):
diff --git a/tools/encfs_aes_getpass.py b/tools/encfs_aes_getpass.py
index 87cc70e..dc9ea34 100755
--- a/tools/encfs_aes_getpass.py
+++ b/tools/encfs_aes_getpass.py
@@ -110,9 +110,9 @@ def main():
 
     sys.stderr.write('Please confirm action on your device.\n')
     passw = client.decrypt_keyvalue(data['bip32_path'],
-                data['label'],
-                binascii.unhexlify(data['password_encrypted_hex']),
-                False, True)
+                                    data['label'],
+                                    binascii.unhexlify(data['password_encrypted_hex']),
+                                    False, True)
 
     print(passw)
 
diff --git a/trezorctl b/trezorctl
index 22e8d0b..31ad968 100755
--- a/trezorctl
+++ b/trezorctl
@@ -13,7 +13,7 @@ from trezorlib.client import TrezorClient, TrezorClientDebug
 def parse_args(commands):
     parser = argparse.ArgumentParser(description='Commandline tool for TREZOR devices.')
     parser.add_argument('-v', '--verbose', dest='verbose', action='store_true', help='Prints communication to device')
-    parser.add_argument('-t', '--transport', dest='transport',  choices=['usb', 'udp', 'serial', 'pipe', 'socket', 'bridge'], default='usb', help="Transport used for talking with the device")
+    parser.add_argument('-t', '--transport', dest='transport', choices=['usb', 'udp', 'serial', 'pipe', 'socket', 'bridge'], default='usb', help="Transport used for talking with the device")
     parser.add_argument('-p', '--path', dest='path', default='', help="Path used by the transport (usually serial port)")
 #    parser.add_argument('-dt', '--debuglink-transport', dest='debuglink_transport', choices=['usb', 'serial', 'pipe', 'socket'], default='usb', help="Debuglink transport")
 #    parser.add_argument('-dp', '--debuglink-path', dest='debuglink_path', default='', help="Path used by the transport (usually serial port)")
@@ -80,7 +80,7 @@ def get_transport(transport_string, path, **kwargs):
         from trezorlib.transport_fake import FakeTransport
         return FakeTransport(path, **kwargs)
 
-    raise NotImplemented("Unknown transport")
+    raise NotImplementedError("Unknown transport")
 
 class Commands(object):
     def __init__(self, client):
@@ -88,7 +88,7 @@ class Commands(object):
 
     @classmethod
     def _list_commands(cls):
-        return [ x for x in dir(cls) if not x.startswith('_') ]
+        return [x for x in dir(cls) if not x.startswith('_')]
 
     def list(self, args):
         # Fake method for advertising 'list' command
@@ -110,7 +110,7 @@ class Commands(object):
         return self.client.features
 
     def list_coins(self, args):
-        return [ coin.coin_name for coin in self.client.features.coins ]
+        return [coin.coin_name for coin in self.client.features.coins]
 
     def ping(self, args):
         return self.client.ping(args.msg, button_protection=args.button_protection, pin_protection=args.pin_protection, passphrase_protection=args.passphrase_protection)
@@ -122,11 +122,11 @@ class Commands(object):
     def set_label(self, args):
         return self.client.apply_settings(label=args.label)
 
-    def set_homescreen(self,args):
+    def set_homescreen(self, args):
         if args.filename:
             from PIL import Image
             im = Image.open(args.filename)
-            if im.size != (128,64):
+            if im.size != (128, 64):
                 raise Exception('Wrong size of the image')
             im = im.convert('1')
             pix = im.load()
@@ -150,7 +150,7 @@ class Commands(object):
 
     def recovery_device(self, args):
         return self.client.recovery_device(args.words, args.passphrase_protection,
-                                    args.pin_protection, args.label, 'english')
+                                           args.pin_protection, args.label, 'english')
 
     def load_device(self, args):
         if not args.mnemonic and not args.xprv:
@@ -159,11 +159,13 @@ class Commands(object):
         if args.mnemonic:
             mnemonic = ' '.join(args.mnemonic)
             return self.client.load_device_by_mnemonic(mnemonic, args.pin,
-                        args.passphrase_protection, args.label, 'english', args.skip_checksum)
-
+                                                       args.passphrase_protection,
+                                                       args.label, 'english',
+                                                       args.skip_checksum)
         else:
             return self.client.load_device_by_xprv(args.xprv, args.pin,
-                        args.passphrase_protection, args.label, 'english')
+                                                   args.passphrase_protection,
+                                                   args.label, 'english')
 
     def reset_device(self, args):
         return self.client.reset_device(True, args.strength, args.passphrase_protection,
@@ -296,14 +298,14 @@ class Commands(object):
 
     set_label.arguments = (
         (('-l', '--label',), {'type': str, 'default': ''}),
-#        (('-c', '--clear'), {'action': 'store_true', 'default': False})
+        # (('-c', '--clear'), {'action': 'store_true', 'default': False})
     )
 
     set_homescreen.arguments = (
         (('-f', '--filename',), {'type': str, 'default': ''}),
     )
     change_pin.arguments = (
-         (('-r', '--remove'), {'action': 'store_true', 'default': False}),
+        (('-r', '--remove'), {'action': 'store_true', 'default': False}),
     )
 
     wipe_device.arguments = ()
diff --git a/trezorlib/ckd_public.py b/trezorlib/ckd_public.py
index 3a12044..7f49d28 100644
--- a/trezorlib/ckd_public.py
+++ b/trezorlib/ckd_public.py
@@ -99,7 +99,7 @@ def serialize(node, version=0x0488B21E):
     s += node.chain_code
     if node.private_key:
         s += '\x00' + node.private_key
-    else :
+    else:
         s += node.public_key
     s += tools.Hash(s)[:4]
     return tools.b58encode(s)
diff --git a/trezorlib/debuglink.py b/trezorlib/debuglink.py
index f2c7cd5..f3120ce 100644
--- a/trezorlib/debuglink.py
+++ b/trezorlib/debuglink.py
@@ -51,7 +51,7 @@ class DebugLink(object):
         # We have to encode that into encoded pin,
         # because application must send back positions
         # on keypad, not a real PIN.
-        pin_encoded = ''.join([ str(matrix.index(p) + 1) for p in pin])
+        pin_encoded = ''.join([str(matrix.index(p) + 1) for p in pin])
 
         print("Encoded PIN:", pin_encoded)
         return pin_encoded
diff --git a/trezorlib/protobuf_json.py b/trezorlib/protobuf_json.py
index 042ef42..64a5f47 100644
--- a/trezorlib/protobuf_json.py
+++ b/trezorlib/protobuf_json.py
@@ -37,15 +37,14 @@ Provide serialization and de-serialization of Google's protobuf Messages into/fr
 # Note that preservation of unknown fields is currently not available for Python (c) google docs
 # extensions is not supported from 0.0.5 (due to gpb2.3 changes)
 
-__version__='0.0.5'
-__author__='Paul Dovbush <dpp@dpp.su>'
-
-
 import json
 from google.protobuf.descriptor import FieldDescriptor as FD
 import binascii
 from . import types_pb2 as types
 
+__version__ = '0.0.5'
+__author__ = 'Paul Dovbush <dpp@dpp.su>'
+
 class ParseError(Exception): pass
 
 
@@ -82,7 +81,7 @@ def pb2json(pb):
     js = {}
     # fields = pb.DESCRIPTOR.fields #all fields
     fields = pb.ListFields()    #only filled (including extensions)
-    for field,value in fields:
+    for field, value in fields:
         if field.type == FD.TYPE_MESSAGE:
             ftype = pb2json
         elif field.type == FD.TYPE_ENUM:
diff --git a/trezorlib/qt/pinmatrix.py b/trezorlib/qt/pinmatrix.py
index 4eaabde..ce2a7c6 100644
--- a/trezorlib/qt/pinmatrix.py
+++ b/trezorlib/qt/pinmatrix.py
@@ -1,10 +1,8 @@
 from __future__ import print_function
-
 import sys
 import math
-import operator
 from PyQt4.QtGui import (QPushButton, QLineEdit, QSizePolicy, QRegExpValidator, QLabel,
-                        QApplication, QWidget, QGridLayout, QVBoxLayout, QHBoxLayout)
+                         QApplication, QWidget, QGridLayout, QVBoxLayout, QHBoxLayout)
 from PyQt4.QtCore import QObject, SIGNAL, QRegExp, Qt
 
 class PinButton(QPushButton):
diff --git a/trezorlib/transport.py b/trezorlib/transport.py
index 4cdbf24..9ff25df 100644
--- a/trezorlib/transport.py
+++ b/trezorlib/transport.py
@@ -77,7 +77,7 @@ class Transport(object):
             return None
 
         data = self._read()
-        if data == None:
+        if data is None:
             return None
 
         return self._parse_message(data)
diff --git a/trezorlib/transport_bridge.py b/trezorlib/transport_bridge.py
index 5134827..75ce071 100644
--- a/trezorlib/transport_bridge.py
+++ b/trezorlib/transport_bridge.py
@@ -1,9 +1,8 @@
 '''BridgeTransport implements transport TREZOR Bridge (aka trezord).'''
 
-import requests
 import json
+import requests
 from . import protobuf_json
-from . import mapping
 from . import messages_pb2 as proto
 from .transport import Transport
 
@@ -21,7 +20,7 @@ class BridgeTransport(Transport):
 
         self.session = None
         self.response = None
-        self.conn = requests.Session();
+        self.conn = requests.Session()
 
         super(BridgeTransport, self).__init__(device, *args, **kwargs)
 
@@ -81,7 +80,7 @@ class BridgeTransport(Transport):
             self.response = r.json()
 
     def _read(self):
-        if self.response == None:
+        if self.response is None:
             raise Exception('No response stored')
         cls = getattr(proto, self.response['type'])
         inst = cls()
diff --git a/trezorlib/transport_hid.py b/trezorlib/transport_hid.py
index 9b27859..57f36db 100644
--- a/trezorlib/transport_hid.py
+++ b/trezorlib/transport_hid.py
@@ -5,7 +5,7 @@ import time
 from .transport import Transport, ConnectionError
 
 DEVICE_IDS = [
-#    (0x10c4, 0xea80),  # TREZOR Shield
+    # (0x10c4, 0xea80),  # TREZOR Shield
     (0x534c, 0x0001),  # TREZOR
 ]
 
diff --git a/trezorlib/transport_pipe.py b/trezorlib/transport_pipe.py
index fe3ca57..5faa219 100644
--- a/trezorlib/transport_pipe.py
+++ b/trezorlib/transport_pipe.py
@@ -1,12 +1,11 @@
 from __future__ import print_function
-
-'''PipeTransport implements fake wire transport over local named pipe.
-Use this transport for talking with trezor simulator.'''
-
 import os
 from select import select
 from .transport import Transport
 
+"""PipeTransport implements fake wire transport over local named pipe.
+Use this transport for talking with trezor simulator."""
+
 class PipeTransport(Transport):
     def __init__(self, device, is_device, *args, **kwargs):
         self.is_device = is_device # Set True if act as device
diff --git a/trezorlib/transport_serial.py b/trezorlib/transport_serial.py
index 6109173..e9b1cec 100644
--- a/trezorlib/transport_serial.py
+++ b/trezorlib/transport_serial.py
@@ -4,8 +4,8 @@ from __future__ import print_function
 
 # Local serial port loopback: socat PTY,link=COM8 PTY,link=COM9
 
-import serial
 from select import select
+import serial
 from .transport import Transport
 
 class SerialTransport(Transport):
diff --git a/trezorlib/tx_api.py b/trezorlib/tx_api.py
index c7d0832..5ef2b49 100644
--- a/trezorlib/tx_api.py
+++ b/trezorlib/tx_api.py
@@ -1,17 +1,19 @@
 import binascii
-import json
 from decimal import Decimal
 # from filecache import filecache, DAY
-from . import types_pb2 as proto_types
 import requests
+from . import types_pb2 as proto_types
+
+def fetch_json(url):
+    try:
+        r = requests.get(url, headers={'User-agent': 'Mozilla/5.0'})
+        return r.json()
+    except:
+        raise Exception('URL error: %s' % url)
 
 def insight_tx(url, rawdata=False):
     if not rawdata:
-        try:
-            r = requests.get(url, headers = {'User-agent': 'Mozilla/5.0'})
-            data = r.json()
-        except:
-            raise Exception('URL error: %s' % url)
+        data = fetch_json(url)
     else:
         data = url
 
@@ -42,11 +44,7 @@ def insight_tx(url, rawdata=False):
 
 def smartbit_tx(url, rawdata=False):
     if not rawdata:
-        try:
-            r = requests.get(url, headers = {'User-agent': 'Mozilla/5.0'})
-            data = r.json()
-        except:
-            raise Exception('URL error: %s' % url)
+        data = fetch_json(url)
     else:
         data = url