Python 3.8 MacOS 11.0.1

0. pip3 install virtualenv
1. python3 -m venv env
2. . ./env/bin/activate
3. pip3 install -r libs.txt
4. Install graphviz. Brew: brew install graphviz
5. Add sourcecode in the <input_file_name>.txt
6. python3 parser.py <input_file_name>.txt <output_file_name>.png
7. Result of execution: the abstract syntax tree is in the <output_file_name>.png