     /// having to figure out if they'll be queueing additional operations (they won't).
     ///
     class DOMString {
-        
+
+        private static let headerLevels: [StandardElementType] = [.h1, .h2, .h4, .h5, .h6]
+
         private lazy var editContext: EditContext = {
             return EditContext(undoManager: self.domUndoManager)
         }()

                self?.applyElement(elementType, spanning: range)
            }
        }
        // MARK: - Styles to HTML elements
        
        /// Applies a standard HTML element to the specified range.

            }
        }

        private func elementTypeForHeaderLevel(_ headerLevel: Int) -> StandardElementType? {
            if headerLevel < 1 && headerLevel > DOMString.headerLevels.count {
                return nil
