input: Write a python function to extract all href links from a given URL.
  assert extract_links("https://www.example.com") == ["https://www.example.com/page1", "https://www.example.com/page2"]
  assert extract_links("https://www.test.com") == ["https://www.test.com/about", "https://www.test.com/contact"]
  assert extract_links("https://www.nolinks.com") == []
output: def extract_links(url):
      import requests
      from bs4 import BeautifulSoup
  
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
  
      links = []
      for a_tag in soup.find_all('a', href=True):
          links.append(a_tag['href'])
  
      return links