anchor.diff:          end
   
   /// A collection of component stores.
  -and 'w Archetype (storeTypes : Dictionary<string, Type>, terms : Terms) =
  +and 'w Archetype (storeTypes : Dictionary<string, Type>, terms : Dictionary<string, Term>) =
   
       let mutable freeIndex = 0
       let freeList = hashSetPlus<int> HashIdentity.Structural []
  
positive.code: /// TODO: consider embedding hash code to make look-ups faster.
  type [<CustomEquality; NoComparison>] ArchetypeId =
      { ComponentNames : string HashSet
        Terms : Terms }
  
      static member inline Hash (hashSet : _ HashSet) =
          let mutable h = 0
  
negative.code:             result
          else false
  
  type [<StructuralEquality; NoComparison>] Subquery =
      | Wildcard // matches everything
      | Eq of Term
  