input: from typing import List
  
  def extract_urls(webpages: List[str]) -> List[str]:
      """ Extracts URLs from a list of webpages using BeautifulSoup.
      >>> extract_urls(["<url_of_webpage1>", "<url_of_webpage2>"])
      ['<url1>', '<url2>', '<url3>', ...]
      """
      import requests
      from bs4 import BeautifulSoup
      urls = []
      for webpage in webpages:
          webpage_content = requests.get(webpage)
          soup = BeautifulSoup(webpage_content.content, 'html.parser')
          links = soup.find_all('a')
          for link in links:
              urls.append(link.get('href'))
      return urls
output:     import requests
      from bs4 import BeautifulSoup
      urls = []
      for webpage in webpages:
          webpage_content = requests.get(webpage)
          soup = BeautifulSoup(webpage_content.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