input: Write a python function to get the number of subscribers from a YouTube channel using BeautifulSoup and requests libraries.
  assert get_subscriber_count('https://www.youtube.com/user/mahalo') > 0
  assert type(get_subscriber_count('https://www.youtube.com/user/mahalo')) == int
  assert get_subscriber_count('https://www.youtube.com/user/nonexistentchannel') == 0
output: def get_subscriber_count(channel_url):
      import requests
      from bs4 import BeautifulSoup
      
      try:
          response = requests.get(channel_url)
          if response.status_code != 200:
              return 0
          
          soup = BeautifulSoup(response.content, 'html.parser')
          subscriber_count_tag = soup.find('yt-formatted-string', {'id': 'subscriber-count'})
          
          if not subscriber_count_tag:
              return 0
          
          subscriber_count_text = subscriber_count_tag.text.strip()
          # Assuming the subscriber count is in the format 'X subscribers'
          count_str = subscriber_count_text.split(' ')[0].replace(',', '')
          
          return int(count_str)
      except Exception as e:
          return 0