input: Write a python function to scrape article titles from a given URL using Scrapy.
  assert scrape_titles('http://www.example.com/news/') == ['Article 1', 'Article 2', 'Article 3']
  assert scrape_titles('http://www.example.com/news/') == ['Breaking News', 'Latest Update', 'Top Story']
output: def scrape_titles(url):
      import scrapy
      from scrapy.crawler import CrawlerProcess
  
      class ArticleSpider(scrapy.Spider):
          name = 'article_spider'
          start_urls = [url]
  
          def parse(self, response):
              titles = response.xpath('//h2/text()').getall()
              return titles
      
      process = CrawlerProcess(settings={"LOG_LEVEL": "ERROR"})
      spider = ArticleSpider()
      process.crawl(spider)
      process.start()
  
      return spider.parse(scrapy.http.Response(url=url))