public CombinationExpression(AssetsExpression parent, string name)
 {
     _parent = parent;
     _name   = name;
 }
 public AliasExpression(AssetsExpression parent, string aliasName)
 {
     _parent    = parent;
     _aliasName = aliasName;
 }
 public OrderedSetExpression(AssetsExpression parent, string setName)
 {
     _parent  = parent;
     _setName = setName;
 }
 public AssetFileExpression(AssetsExpression parent, string assetName)
 {
     _parent       = parent;
     _assetName    = assetName;
     _registration = _parent._registration.Value;
 }