function ArrayOperation (operation, count, items) {
  this.type = operation; // RETAIN | INSERT | DELETE
  this.count = count;
  this.items = items;
}
function ArrayOperation (operation, count, items) {
  this.type = operation; // RETAIN | INSERT | DELETE
  this.count = count;
  this.items = items;
}
function ArrayOperation ( operation , count , items ) { this . type = operation ; // RETAIN | INSERT | DELETE this . count = count ; this . items = items ; }
Internal data structure to represent an array operation.

@method ArrayOperation
@private
@param {string} type The type of the operation.  One of
`Ember.TrackedArray.{RETAIN, INSERT, DELETE}`
@param {number} count The number of items in this operation.
@param {array} items The items of the operation, if included.  RETAIN and
INSERT include their items, DELETE does not.
Internal data structure to represent an array operation .