We can mostly follow Google Python Style Guide.
All module-level functions and class/object methods should be annotated with type hints. For other values, type hints should be used where it seems important. See PEP 0484.
Later we might use mypy. Currently it doesn't work well will Python 3.5.
We use pytest.
We will use Sphinx for creating documentation. Docstrings in the code should therefore use Sphinx directives, see this example.