Reproduce environments

Reproducible and secure Python environments are difficult to ensure. With the Python package manager pip, the call would look like this:

$ python -m pip install --no-deps --require-hashes ----only-binary=:all:

Dedicated environments (for example with Pipenv, devpi and Spack simplify this if you save the file with ther specifications, for example Pipfile, Pipfile.lock, package-lock.json etc. In this way, you and others can reproduce the environments.