<s>[INST] python ImportError No module named I am very new at Python and I am getting this error:
Traceback (most recent call last):
  File "mountain.py", line 28, in ?
    from toolkit.interface import interface
ImportError: No module named toolkit.interface

Python is installed in a local directory:
My directory tree is like this:
(local directory)/site-packages/toolkit/interface.py

My code is in here 
(local directory)/site-packages/toolkit/examples/mountain.py

To run the example I do python mountain.py, and in the code I have:
from toolkit.interface import interface

And i get the error that I wrote, I have already checked sys.path and there I have the directory /site-packages, also I have the file __init__.py.bin in the toolkit folder to indicate to Python that this is a package. I also have a __init__.py.bin in the examples directory.
I do not know why Python cannot find the file when it is in sys.path, any ideas? Can be a permissions problem? Do I need execution permission?
 [/INST] Based on your comments to orip's post, I guess this is what happened:

You edited __init__.py on windows.
The windows editor added something non-printing, perhaps a carriage-return (end-of-line in Windows is CR/LF; in unix it is LF only), or perhaps a CTRL-Z (windows end-of-file).
You used WinSCP to copy the file to your unix box.
WinSCP thought: "This has something that's not basic text; I'll put a .bin extension to indicate binary data."
The missing __init__.py (now called __init__.py.bin) means python doesn't understand toolkit as a package.
You create __init__.py in the appropriate directory and everything works... ?

 </s>