input: 
  from typing import List
  from bs4 import BeautifulSoup
  import requests
  
  def extract_urls(webpages: List[str]) -> List[str]:
      """Extracts URLs from a list of webpages using BeautifulSoup.
      >>> extract_urls(["<url_of_webpage>"])
      ['<url1>', '<url2>', ...]
      """
      urls = []
      for webpage in webpages:
          webpage_content = requests.get(webpage).content
          soup = BeautifulSoup(webpage_content, 'html.parser')
          links = soup.find_all('a')
          for link in links:
              urls.append(link.get('href'))
      return urls
  
output:     urls = []
      for webpage in webpages:
          webpage_content = requests.get(webpage).content
          soup = BeautifulSoup(webpage_content, 'html.parser')
          links = soup.find_all('a')
          for link in links:
              href = link.get('href')
              if href and href.startswith('http'):
                  urls.append(href)
      return urls