/* Convert to a string, using the "PropertyList" format;
Indent is for human-readibility;
level==0 means top level; level==1 => 4 spaces */
@end
/*************** Mutable Abstract Class ***************/
@interface NSMutableArray: NSArray
/* Note: Only the 3 first methods are necessary for the Array abstraction. However, in order to enable subclasses to meaningfully implement certain functions (i.e. notification), all classes implementing the NSMutableArray should implement all 5 methods, and no method should call recursively any of the others */
- (void)addObject:anObject;
/* Appends element at end of array; Resizes if necessary;
-retain is applied to the object inserted;
If object is nil an exception is raised;
Clients can expect this method to be fast, in O(1) */