my_inventory:
    type: inventory
    inventory: chest
    title: <&a>Hi!
    slots:
        - [] [] [] [] [] [] [] [] []
        - [] [] [] [] [] [] [] [] []
        - [b] [f] [f] [f] [f] [f] [f] [f] [r_a]
    definitions:
        b: back
        r_a: right_arrow
        f: filler

filler:
    type: item
    material: glass_pane

back:
    type: item
    material: oak_door
    lore:
    - <&7>Click to go back!

right_arrow:
    type: item
    material: arrow
    lore:
    - <&7>Click to go forward!

inventory_filler:
    type: task
    definitions: player|items
    script:
        - define inventory <inventory[my_inventory]>
        - inventory set origin:<[items]> destination:<[inventory]>
        - inventory open player:<[player]> destination:<[inventory]>

test_filler:
    type: task
    definitions: type
    script:
        - choose <[type]>:
            - case 1:
                - define items <list[<item[dirt]>|<item[acacia_boat]>|<item[polished_basalt]>]>
            - case 2:
                - define items <list[<item[acacia_pressure_plate]>|<item[oak_planks]>|<item[diamond]>]>
            - case 3:
                - define items <list[<item[black_banner]>|<item[milk_bucket]>|<item[cocoa_beans]>]>
        - run inventory_filler def.player:<player> def.items:<[items]>