defaults = {
    'apt': {
        # https://github.com/rbenv/ruby-build/wiki#ubuntudebianmint
        'packages': {
            'autoconf': {},
            'bison': {},
            'patch': {},
            'build-essential': {},
            'rustc': {},
            'libssl-dev': {},
            'libyaml-dev': {},
            'libreadline-dev': {},
            'zlib1g-dev': {},
            'libgmp-dev': {},
            'libncurses5-dev': {},
            'libffi-dev': {},
            'libgdbm6': {},
            'libgdbm-dev': {},
            'libdb-dev': {},
            'uuid-dev': {},
        },
    },
    'rbenv': set(),
}