Fork dlce-eva/python-newick and install the development environment:
$ pip install virtualenv # might require sudo/admin privileges
$ git clone https://github.com/<YOUR-GITHUB-HANDLE>/python-newick.git
$ cd python-newick
$ python -m virtualenv .venv
$ source .venv/bin/activate # Windows: .venv\Scripts\activate.bat
$ pip install -r requirements.txt # installs the cloned version with dev-tools in development mode