[Scripting Question] How do I check the amount of items in the bag and in the PC item storage?

[DarkraiMaker]

How do I check the amount of items in the bag and in the PC item storage?
This function:

 def pbQuantity(item)
    item = getID(PBItems,item)
    if !item || item<1
      raise ArgumentError.new(_INTL("Item number {1} is invalid.",item))
    end
    pocket = pbGetPocket(item)
    maxsize = maxPocketSize(pocket)
    maxsize = @pockets[pocket].length if maxsize<0
    return ItemStorageHelper.pbQuantity(@pockets[pocket],maxsize,item)
  end

Checks a specific item, how can I go through all pockets?
essentials v18.1