return function(mod)
  mod.content.items:register("MODBERRY", {
    id = "MODBERRY", name = "MODBERRY", price = 250, tossable = true,
    effect = "MODBERRY_EFFECT",
  })
  mod.content.item_effects:register("MODBERRY_EFFECT", {
    field = true, battle = false, needsTarget = true,
    use = function(ctx)
      local mon = ctx.target
      local max = mon and (mon.maxHp or mon.stats.hp)
      if not mon or mon.hp <= 0 or mon.hp >= max then
        return "failed", { "It had no effect." }
      end
      mon.hp = math.min(max, mon.hp + 10)
      return "consumed", { "Restored 10 HP!" }
    end,
  })
  mod.content.text_pointers:patch("ViridianMart", {
    TEXT_VIRIDIANMART_CLERK = { mart = { __append = { "MODBERRY" } } },
  })
end