Set up or update a reveals.js presentation with slides written in markdown.

    Several reveal.js plugins will be set up, too.

    More info:
      Demo: https://theno.github.io/revealjs_template
      http://lab.hakim.se/reveal-js/
      https://github.com/hakimel/reveal.js
      plugins:
        https://github.com/hakimel/reveal.js/wiki/Plugins,-Tools-and-Hardware
        https://github.com/rajgoel/reveal.js-plugins/
        https://github.com/e-gor/Reveal.js-TOC-Progress
        https://github.com/e-gor/Reveal.js-Title-Footer

def revealjs(basedir=None, title=None, subtitle=None, description=None,
             github_user=None, github_repo=None):
    '''Set up or update a reveals.js presentation with slides written in markdown.

    Several reveal.js plugins will be set up, too.

    More info:
      Demo: https://theno.github.io/revealjs_template
      http://lab.hakim.se/reveal-js/
      https://github.com/hakimel/reveal.js
      plugins:
        https://github.com/hakimel/reveal.js/wiki/Plugins,-Tools-and-Hardware
        https://github.com/rajgoel/reveal.js-plugins/
        https://github.com/e-gor/Reveal.js-TOC-Progress
        https://github.com/e-gor/Reveal.js-Title-Footer
    '''
    basedir = basedir or query_input('Base dir of the presentation?',
                                     default='~/repos/my_presi')
    revealjs_repo_name = 'reveal.js'
    revealjs_dir = flo('{basedir}/{revealjs_repo_name}')

    _lazy_dict['presi_title'] = title
    _lazy_dict['presi_subtitle'] = subtitle
    _lazy_dict['presi_description'] = description
    _lazy_dict['github_user'] = github_user
    _lazy_dict['github_repo'] = github_repo

    question = flo("Base dir already contains a sub dir '{revealjs_repo_name}'."
                   ' Reset (and re-download) reveal.js codebase?')
    if not exists(revealjs_dir) or query_yes_no(question, default='no'):
        run(flo('mkdir -p {basedir}'))
        set_up_revealjs_codebase(basedir, revealjs_repo_name)
        install_plugins(revealjs_dir)
        apply_customizations(repo_dir=revealjs_dir)
    if exists(revealjs_dir):
        install_files_in_basedir(basedir, repo_dir=revealjs_dir)
        init_git_repo(basedir)
        create_github_remote_repo(basedir)
        setup_npm(revealjs_dir)
    else:
        print('abort')