Catmandu::Fix::Bind::each3pm

    # Create a hash:
    # demo:
    #   nl: 'Tuin der lusten'
    #   en: 'The Garden of Earthly Delights'
    # Create a list of all the titles, without the language tags.
    do each(path: demo, var: t)
        copy_field(t.value, titles.$append)
    end
    # This will result in:
    # demo:
    #   nl: 'Tuin der lusten'
    #   en: 'The Garden of Earthly Delights'
    # titles:
    #   - 'Tuin der lusten'
    #   - 'The Garden of Earthly Delights'
    # Upcase every key in the root hash
    # foo: bar
    # test: 1234
    do each(path:., var: t)
       upcase(t.key)
    end
    # This will result in
    # FOO: bar
    # TEST: 1234