[sadra84]

I'v read this page and done it step by step:
1- I downloaded the source code from github
2- I set environment variable CALIBRE_DEVELOP_FROM
after these steps I started calibre but error message appears. I used calibre-debug to find a problem:

Python function terminated unexpectedly
  'module' object has no attribute 'zip' (Error Code: 1)
Traceback (most recent call last):
  File "site.py", line 101, in main
  File "site.py", line 77, in run_entry_point
  File "C:\Users\*****\Downloads\Compressed\calibre-master\src\calibre\__init__.py", line 9, in <module>
    from polyglot.builtins import codepoint_to_chr, unicode_type, range, hasenv, native_string_type
  File "C:\Users\*****\Downloads\Compressed\calibre-master\src\polyglot\builtins.py", line 69, in <module>
    zip = builtins.zip
AttributeError: 'module' object has no attribute 'zip'

then I went to builtins.py and add

print(builtins.__file__)

before

zip = builtins.zip
map = builtins.map
filter = builtins.filter
range = builtins.range

and the output was:

C:\Users\*****\Downloads\Compressed\calibre-master\src\polyglot\builtins.py

which is the path of builtins.py itself
I can't understand what does buitins.py do. Please explain it and help me to solve the problem
Thanks