declare module "estree-walker" {
  export interface Node {
    start: number;
    end: number;
    type: string;
    [propName: string]: any;
  }

  export type WalkerListener = (node: Node, parent?: Node, prop?: string, index?: number) => void;

  export interface WalkerOptions {
    enter?: WalkerListener;
    leave?: WalkerListener;
  }

  export function walk(ast: Node, options: WalkerOptions): void;
}