Code style

Read pep8 and use it as first place style guide

These rules may add, overwrite or emphasize pep8 ones:

• Don't put large code with multiple actions in one line. Split it into several lines in accordance with functional logic
• Give sensible names for functions, vars and constants. Function's name should be started with verb and shortly describe what func do. Constants should be written using UPPER case and placed at the top of file