System/Library/PrivateFrameworks/ATFoundation.framework
ATInternalError.h
@interface ATInternalError : NSObject
+ (id)errorWithCode:(unsigned long long)a0 format:(id)a1;
+ (id)errorWithCode:(unsigned long long)a0 underlyingError:(id)a1;
+ (id)errorWithPosixError:(int)a0 format:(id)a1;
@end