Peekable item for user-defined functions and variables
Inheritance: PeekItemBase
 public UserDefinedItemPeekResultSource(UserDefinedPeekItem peekItem) {
     _peekItem = peekItem;
 }
 public UserDefinedItemPeekResultSource(UserDefinedPeekItem peekItem)
 {
     _peekItem = peekItem;
 }