input: Write a function to extract the titles of all YouTube videos from a given URL. Return a list of titles or an empty list if no titles are found.
  import requests
  import re
  
  def extract_youtube_titles(url):
      r = requests.get(url)
      titles = re.findall('<a href="/watch\?v=([^"]+)">(.+?)<\/a>', r.content.decode('utf-8'))
      return [title[1] for title in titles]
  
  assert extract_youtube_titles("https://www.youtube.com/user/Thexvid/videos") == ["Video Title 1", "Video Title 2"]
  assert extract_youtube_titles("https://www.youtube.com/user/NoVideosHere/videos") == []
  assert extract_youtube_titles("https://www.youtube.com/user/VideoChannel/videos") == ["Another Video Title", "Yet Another Video"]
  assert extract_youtube_titles("https://www.youtube.com/user/EmptyChannel/videos") == []
output: def extract_youtube_titles(url):
      r = requests.get(url)
      titles = re.findall('<a href="/watch\?v=([^"]+)">(.+?)<\/a>', r.content.decode('utf-8'))
      return [title[1] for title in titles]