- GitHub Actions complains about missing hashes in poetry's export
  of pinned dependencies
- as an example, see https://github.com/webartifex/urban-meal-delivery/runs/1550750320

- create the global `config` object inside the
  `urban_meal_delivery.configuration` module
- streamline documentation and comments

zsh-dotenv automatically loads the environment variables upon entering
the project's root.

... after upgrading:
- dev dependencies
  + packaging
  + pre-commit
  + pytest
  + sphinx
- research dependencies
  + pandas
- transient dependencies
  + appnode   + argcomplete        + babel         + bandit
  + certifi   + cffi               + colorlog      + darglint
  + identify  + ipykernel          + jupyter-core  + nest-asyncio
  + pathspec  + prometheus-client  + py            + pygments
  + pywin32   + pyzmq              + regex         + requests
  + restructedtext-lint            + stevedore     + testfixtures
  + urllib3   + virtualenv

The paper is now published.

... to assume a feature branch if the branch name does not start with
'release' or 'research' and change all references into 'develop'.

... after upgrading:
- sqlalchemy
- dev dependencies
  + darglint
  + flake8(-comprehensions)
  + pre-commit
  + pytest
  + sphinx(-autodoc-typehints)
- reseach dependencies
  + jupyterlab
  + numpy
  + pandas
  + pytz
- transient dependencies
  + attrs
  + colorama
  + gitpython
  + identify
  + iniconfig
  + ipython
  + nbclient
  + nbconvert
  + nbformat
  + nest-asyncio
  + notebook
  + pandocfilters
  + pbr
  + prompt-toolkit
  + pygments
  + regex
  + testfixtures
  + toml
  + tornado
  + traitlets
  + urllib3
  + virtualenv

The order of keys in the poetry.lock file is changed.

- clean the raw data given by the undisclosed meal delivery platform:
  + keep data only for the three target citis:
    * Bordeaux
    * Lyon
    * Paris
  + merge duplicates
    * it appears as redundant addresses were created
      for each order by the same customer
      =>  significant reduction in the number of addresses
    * propagate the merges to the other tables
      that reference records merged away
  + cast data types and keep their scopes narrow
  + normalize the data
  + remove obvious outliers
  + adjust/discard unplausible values
- map the cleaned data onto the ORM models
- store the cleaned data in a new database schema

.. after upgrading a couple of packages

- change references to temporary branches (e.g., "release-*" and
  "publish") to point to the 'main' branch
- add --branch=BRANCH_NAME option to the nox session so that
  one can pass in a target branch to make all references point to
- run "fix-branch-references" as the first pre-commit hook
  as it fails the fastest
- bug fix: allow dots in branch references (e.g., "release-0.1.0")

- dependencies used to run the Jupyter Lab environment that are not
  required by the `urban-meal-delivery` package itself are put into
  an installation extra called "research"
- this allows to NOT install the requirements, for example, when
  testing the package in an isolated environment

- run "format" and "lint" separately
  => remove the nox session "pre-commit"
- execute the entire "test-suite" before merges
  + rename "pre-merge" into "test-suite"
  + do not "format" and "lint" here any more
  + do not execute this before pushes
    * allow branches with <100% test coverage to exist on GitHub
      (they cannot be merged into 'main' until 100% coverage)
    * GitHub Actions executes the test suite

- many *.py and *.ipynb files will contain links to resources on
  GitHub or nbviewer that have branch references in them
- add a pre-commit hook implemented as the nox session
  "fix-branch-references" that goes through these files and
  changes all the branch labels to the current one

- some glob patterns in .gitignore were not correctly expanded
- adapt the exclude logic to focus on the start of the excluded paths

- use Alembic to migrate the PostgreSQL database
  + create initial migration script to set up the database,
    as an alternative to db.Base.metadata.create_all()
  + integrate Alembic into the test suite; the db_engine fixture
    now has two modes:
    * create the latest version of tables all at once
    * invoke `alembic upgrade head`
    => the "e2e" tests are all run twice, once in each mode; this
       ensures that the migration scripts re-create the same database
       schema as db.Base.metadata.create_all() would
    * in both modes, a temporary PostgreSQL schema is used to create the
      tables in
    => could now run "e2e" tests against production database and still
       have isolation
- make the configuration module public (to be used by Alembic)
- adjust linting rules for Alembic

- use SQLAlchemy (and PostgreSQL) to model the ORM layer
- add the following models:
  + Address => modelling all kinds of addresses
  + City => model the three target cities
  + Courier => model the UDP's couriers
  + Customer => model the UDP's customers
  + Order => model the orders received by the UDP
  + Restaurant => model the restaurants active on the UDP
- so far, the emphasis lies on expression the Foreign Key
  and Check Constraints that are used to validate the assumptions
  inherent to the cleanded data
- provide database-independent unit tests with 100% coverage
- provide additional integration tests ("e2e") that commit data to
  a PostgreSQL instance to validate that the constraints work
- adapt linting rules a bit

... after upgrading:
- flake8-plugin-utils
- sphinx

- add the following file:
  + src/urban_meal_delivery/_config.py
- a config module is created holding two sets of configurations:
  + production => against the real database
  + testing => against a database with test data
- the module is "protected" (i.e., underscore) and imported at the
  top level via a proxy-like object `config` that detects in which of
  the two environments the package is being run

- only support Python 3.8 in the project
  as GitHub Actions has no 3.9 in its base image
- re-order some sessions so that the order in
  `poetry run nox --list` is more intuitive
- add extensive documentation to the noxfile.py module
- add more whitespace to noxfile.py to make it easier to read
- add generic maintainance tasks:
  + "init-project" => set up all pre-commit hooks
  + "clean-pwd" => ~ `git clean -X` with minor exceptions
- upgrade isort to 5.3.0

- use sphinx to document the developed package
- create a nox session "docs" that builds the docs
- include a skeleton in the docs/ folder
  + how to install the package
  + how to use nox
  + license

- use xdoctest to validate all code snippets in docstrings
- add xdoctest to the nox session "test"

- add a nox session "safety"

- for tests/ and the noxfile.py, type annotations are not strictly
  enforced any more
  + this simplifies the way test cases and nox sessions are written
  + for many pytest fixtures, no types are available via a public API
- put fixtures inside the classes the corresponding test cases are
  grouped in

- add the following file:
  + src/urban_meal_delivery/console.py => click-based CLI tools
  + tests/test_console.py => tests for the module above
- add a CLI entry point `umd`:
  + implement the --version / -V option
    to show the installed package's version
  + rework to package's top-level:
    * add a __pkg_name__ variable to parameterize the package name
  + add unit and integration tests
- fix that pylint cannot know the proper order of imports in the
  isolated nox session