input: Write a function to get Instagram followers count given a username.
  assert get_instagram_followers('instagram') > 0
  assert isinstance(get_instagram_followers('someusername'), int)
  assert get_instagram_followers('nonexistentuser') == 0
output: def get_instagram_followers(username):
      import requests
  
      url = f'https://www.instagram.com/{username}/?__a=1&__d=dis'
      try:
          response = requests.get(url)
          if response.status_code == 200:
              data = response.json()
              return data['graphql']['user']['edge_followed_by']['count']
          else:
              return 0
      except requests.exceptions.RequestException:
          return 0