input: Write a python function to fetch the content of a given URL using requests library.
  assert fetch_content("http://example.com") == requests.get("http://example.com").text
  assert fetch_content("http://httpbin.org/get") == requests.get("http://httpbin.org/get").text
output: def fetch_content(url):
      import requests
      response = requests.get(url)
      return response.text