I have a quick question about item groups. Is there a way to have a reference to another item group within a list of items. For example this:
{
    "type" : "item_group",
    "id" : "forest",
    "items":[
      ["rock", 40],
      ["stick", 95],
      ["pine_bough", 15],
      ["acorns", 15],
      ["pinecone", 5],
      ["one_year_old_newspaper", 2],
      ["months_old_newspaper", 3],
      ["weeks_old_newspaper", 4],
      ["newest_newspaper", 5],
      ["bottle_plastic", 1],
      ["bottle_glass", 1],
      ["syringe", 1],
      ["cig_butt", 1]
    ]
  }
…could be changed to something like this:
{
    "type" : "item_group",
    "id" : "forest",
    "items":[
      ["rock", 40],
      ["stick", 95],
      ["pine_bough", 15],
      ["acorns", 15],
      ["pinecone", 5],
      ["ITEM_GROUP":"trash", 5]
    ]
  }
Or something like that.
Basically a way to nest smaller, more focused item groups in larger ones.