input: from typing import Set, List
  
  def crawl(url: str) -> Set[str]:
      visited = set()
      queue = [url]
  
      while queue:
          curr = queue.pop(0)
          visited.add(curr) 
          response = requests.get(curr)
  
          if response.ok:
              soup = BeautifulSoup(response.text, 'html.parser')
  
              # scrape the page here 
  
              # find all the links
              links = soup.find_all('a', href=re.compile('^http')) 
  
              for link in links:
                  if link['href'] not in visited:
                      queue.append(link['href'])
  
      return visited
  
  """
  >>> crawl('http://example.com')
  {'http://example.com', 'http://example.com/link1', 'http://example.com/link2'}
  >>> crawl('http://another-example.com')
  {'http://another-example.com', 'http://another-example.com/page1', 'http://another-example.com/page2'}
  """
output:     from bs4 import BeautifulSoup
      import requests
      import re
  
      visited = set()
      queue = [url]
  
      while queue:
          curr = queue.pop(0)
          visited.add(curr) 
          response = requests.get(curr)
  
          if response.ok:
              soup = BeautifulSoup(response.text, 'html.parser')
  
              # scrape the page here 
  
              # find all the links
              links = soup.find_all('a', href=re.compile('^http')) 
  
              for link in links:
                  if link['href'] not in visited:
                      queue.append(link['href'])
  
      return visited