Typing is a backport of python3 python module.
Once we have python3 it becomes obsolete.

We ignore all third-party dependencies by default.
This might look verbose on first look however it has the advantage
this way we can easily see if we accidentally add new dependencies
and we can detect typos in local imports.
The alternative would be to ignore all missing imports instead.

cmd is defined later as a string.

Mypy does not like re-imports from different modules.
We can later drop this statement when we switch to python3.

Mypy complaints about this line.
In this file I also added a more comprehensive example for typing annotation.
Note that python3 has a nicer language builtin syntax.
The currently used type annotations will be still compatible with python3 and
can be ported on demand.

For a few container types mypy is not able to interfere the type
automatically. In those cases it asks the user to provide a type
manually.