abstract file class fix

classes/file.py

@@ -1,23 +1,24 @@
 from sys import platform
 import os
 from subprocess import call
-# from os import path  # path.exists() may used in future.. may be..
+from os.path import exists
 
 class File():
   def __init__(self, path):
     self._path = path
 
   def write_bytes(self, bytes):
-    '''  truncates the file and create new with contents :param bytes '''
-    with open(self._path, 'r+b') as file:
-      file.write(bytes)
+    '''  truncates the file and create new with :param bytes.
+     :return number of bytes written'''
+    with open(self._path, 'w+b') as file:
+      return file.write(bytes)
 
   def read_bytes(self):
-    ''' read the file as bytes '''
+    ''' read the file as bytes. :return b'' on file not exist '''
+    if not exists(self._path): return b''
     # buf = b''
     with open(self._path, 'r+b') as file:
-      return file.read()  # is this safe?
-      # buf = file.read()
+      return file.read()
     # return buf
 
   def open(self):