Python is installed in a local directory. 

My directory tree looks 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 write `python mountain.py`, and in the code I have:

```
from toolkit.interface import interface

```

And I get the error:

```
Traceback (most recent call last):
  File "mountain.py", line 28, in ?
    from toolkit.interface import interface
ImportError: No module named toolkit.interface

```

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 it be a permissions problem? Do I need some execution permission?