PEP 8 code format, like:

* trim trailing whitespace
* single or two blank lines
* using single quote if not docstring
* print () -> print()
PEP 8 code format, like:

* add some whitespace, make code more readable
remove repeat "import random"
PEP 8 code format, like:

* remove wildcard import
Merge pull request #2 from akun/master

PEP 8 code format