The package python3 provides a python interpreter that supports virtual environments:

    $ tools/python3/python3.@PYTHON_VERSION_MINOR@ -m venv /path/to/venv
    $ export VIRTUAL_ENV=/path/to/venv
    $ export PATH=/path/to/venv/bin:$PATH
    $ export -n PYTHONHOME
    $ unset PYTHONHOME

    See https://docs.python.org/3/library/venv.html for more details.
