input: Write a function to extract titles of all YouTube videos from a given URL.
  def extract_youtube_titles(url):
      import requests
      import re
  
      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")==['First Video', 'Second Video', 'Third Video']
  assert extract_youtube_titles("https://www.youtube.com/user/AnotherUser/videos")==['Video 1', 'Video 2', 'Video 3']
  assert extract_youtube_titles("https://www.youtube.com/user/EmptyUser/videos")==[]
  assert extract_youtube_titles("https://www.youtube.com/user/NotFoundUser/videos")==[]
output: def extract_youtube_titles(url):
      import requests
      import re
  
      r = requests.get(url)
      titles = re.findall('<a href="/watch\?v=([^"]+)">(.+?)<\/a>', r.content.decode('utf-8'))
      
      return [title[1] for title in titles]