diff --git a/escpos/escpos.py b/escpos/escpos.py
index b0d25ef..40137f7 100644
--- a/escpos/escpos.py
+++ b/escpos/escpos.py
@@ -196,7 +196,7 @@ class Escpos(object):
         outp = b''
         for _ in range(0, out_bytes):
             outp += six.int2byte(inp_number % 256)
-            inp_number = inp_number // 256
+            inp_number //= 256
         return outp
 
     def charcode(self, code):
@@ -481,12 +481,12 @@ class Escpos(object):
         else:
             raise SetVariableError()
         # Upside down
-        if flip == True:
+        if flip:
             self._raw(TXT_FLIP_ON)
         else:
             self._raw(TXT_FLIP_OFF)
         # Smoothing
-        if smooth == True:
+        if smooth:
             self._raw(TXT_SMOOTH_ON)
         else:
             self._raw(TXT_SMOOTH_OFF)
diff --git a/escpos/printer.py b/escpos/printer.py
index 654b995..b6ef158 100644
--- a/escpos/printer.py
+++ b/escpos/printer.py
@@ -277,8 +277,6 @@ class Dummy(Escpos):
 
     def __init__(self, *args, **kwargs):
         """
-
-        :param devfile : Device file under dev filesystem
         """
         Escpos.__init__(self, *args, **kwargs)
         self._output_list = []
diff --git a/test/test_image.py b/test/test_image.py
index fd49797..dbfe5b0 100644
--- a/test/test_image.py
+++ b/test/test_image.py
@@ -54,4 +54,4 @@ def _load_and_check_img(filename, width_expected, height_expected, raster_format
     i = 0 
     for row in im.to_column_format(False):
         assert(row == column_format_expected[i])
-        i = i + 1
+        i += 1
diff --git a/test/test_with_statement.py b/test/test_with_statement.py
index a59a719..71efc24 100644
--- a/test/test_with_statement.py
+++ b/test/test_with_statement.py
@@ -14,7 +14,7 @@ from __future__ import unicode_literals
 
 import escpos.printer as printer
 import escpos.escpos as escpos
-import os
+
 
 def test_with_statement():
     """Use with statement"""