                 dependencies to enforce mutual exclusivity.
             */
             let concurrencyCategories: [String] = op.conditions.flatMap { condition in
-                if !type(of: condition).isMutuallyExclusive { return nil }
+                guard type(of: condition).isMutuallyExclusive else { return nil }
                 
                 return "\(type(of: condition))"
             }

            operation.addCompletionBlock { [weak self, weak operation] in
                guard let queue = self, let operation = operation else { return }
                queue.delegate?.operationQueue?(queue, operationDidFinish: operation, withErrors: [])
                //Remove deps to avoid cascading deallocation error
                //http://stackoverflow.com/questions/19693079/nsoperationqueue-bug-with-dependencies
                operation.dependencies.forEach { operation.removeDependency($0) }
            }
        }
        

                },
                finishHandler: { [weak self] finishedOperation, errors in
                    if let q = self {
                        q.delegate?.operationQueue?(q, operationDidFinish: finishedOperation, withErrors: errors)
                    }
                }
            )
