How to do it...

1. Manually create requirements.txt by typing in the packages to include in the project. The following is an example from https://pip.pypa.io/en/latest/reference/pip_install/#requirements-file-format:

1. Alternatively, run pip freeze > requirements.txt. This automatically directs the currently installed packages to a properly formatted requirements file.
2. To implement hash-checking mode, simply include the digest with the package name in the requirements file, demonstrated below:

      FooProject == 1.2 --hash=sha256:<hash_digest>

Note: Supported hash algorithms include: md5, sha1, sha224, sha384, sha256, and sha512.

1. If there are module conflicts, or special versioning is needed, provide the first module required:

      m1

1. Indicate the second module, but ensure the version installed pre-dates the known bad version:

      m2<1.7

1. Provide the third module, ensuring it is at least equal to the minimum version required, but no greater than the maximum version that can be used:

     m3>=1.5, <=2.0

While the preceding screenshot shows some version specifier requirements, here is an example showing some of the different ways to specify module versions in requirements.txt:

        flask
        flask-pretty == 0.2.0
        flask-security <= 3.0
        flask-oauthlib >= 0.9.0, <= 0.9.4