Code refactoring to a more readable and maintainable one

Original Source: https://gist.github.com/Melevir/5754a1b553eb11839238e43734d0eb79

To set up the environment (Python version: 3.6)

$ virtualenv --python=$(which python3) py $ source py/bin/activate
$ pip install -r requirements.txt

To run the program use the following format, please:

>>> python3 get_words.py <source_type> <POS> <words_count>
    

    :source_type      str: source type. Available: [web, folder]
    :POS         str: (part of speech). Available: [verb, noun]
    :words_count  int: number of words
    

For example:

>>> python3 get_words.py folder verb 105

OR

>>> python3 get_words.py web noun 77