code: function unionizeList(array, start, count, union) {
      var internalObservees = [] // list of observees and their property path
      if(union !== undefined) {
          var afterEnd = start+count
          for(var n=start; n<afterEnd; n++) {
              internalObservees.push({obj: array[n], index: n})
              if(union === true)
                  array[n] = array[n].subject
          }
      }
  
      return internalObservees
  }
docs: sets a slice of elements to their subjects and returns the original observee objects along with their indexes