input: from typing import List
  
  def web_scraper(url: str) -> List[str]:
      """ A function that creates a web scraper to extract all URLs from a given webpage.
      This function utilizes the Python package BeautifulSoup to parse the webpage and
      extract the URLs found within 'a' tags.
      
      >>> web_scraper("https://example.com")
      ['http://example.com/page1', 'http://example.com/page2', 'http://example.com/page3']
      """
output:     import requests
      from bs4 import BeautifulSoup
  
      response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      urls = [a['href'] for a in soup.find_all('a', href=True)]
      return urls