message: Implement getPreviousSibling()
diff: import { NodePath } from "@babel/traverse";
  import * as t from "@babel/types";
  +import { last } from "../array-helpers";
  +
  export {
  + getPreviousSibling,
  hasSiblingStatement,
  getPreviousSiblingStatements,
  getNextSiblingStatements
  };
  +function getPreviousSibling(path: NodePath): NodePath | undefined {
  + return last(path.getAllPrevSiblings());
  +}
  +
  function hasSiblingStatement(path: NodePath): boolean {
  const allSiblingStatements = [
  ...getPreviousSiblingStatements(path),
  