anchor.diff:      sqlalchemy
       sqlalchemy-continuum
       werkzeug
  -    wtforms
  +    pinned_wtforms
       psycopg2
       debts
     ];
  
positive.code: { buildPythonPackage, lib, fetchFromGitHub, isPy27, nixosTests, fetchpatch
  , alembic
  , aniso8601
  , Babel
  
negative.code:     flask-restful
      flask_script
      flask_sqlalchemy
      pinned_flask_wtf
      idna
      itsdangerous
      jinja2
  