input: 
  from bs4 import BeautifulSoup
  import requests
  
  def extract_data(url: str) -> list:
      """ Given a URL of a website, the function extracts all URLs found in the 'a' tags
      of the webpage using the BeautifulSoup library.
      >>> extract_data("<url_of_webpage>")
      ['http://example.com', 'http://another-example.com', ...]
      """
  
output:     response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      urls = [a['href'] for a in soup.find_all('a', href=True)]
      return urls