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/** * An object used to track the state of a traversal, e.g. a `forEach`. */export interface TraverseState {  /**   * Returns true if the traversal has been halted by the user.   */  readonly halted: boolean;  /**   * Returns the current index of the traversal.   */  readonly currentIndex: number;
  /**   * Increases the `currentIndex` of this traversal   * @returns the next index that the traversal should use   */  nextIndex(): number;  /**   * Sets the `halted` value to true.   */  halt(): void;  /**   * Sets the `halted` value to false, and resets the `currentIndex`   * value to its start value.   */  reset(): void;}
class TraverseStateImpl implements TraverseState {  currentIndex: number;  halted = false;
  constructor(readonly startIndex: number) {    this.currentIndex = startIndex;  }
  nextIndex(): number {    return this.currentIndex++;  }
  readonly halt = (): void => {    this.halted = true;  };
  reset(): void {    this.currentIndex = this.startIndex;    this.halted = false;  }}
/** * Returns a new `TraverseState` instance, using optionally given `startIndex` as a start * index value. * @param startIndex - (default: 0) the start index to use */export function TraverseState(startIndex = 0): TraverseState {  return new TraverseStateImpl(startIndex);}