input: Write a python function to get the biography of an artist using the MusicBrainz API.
  assert get_biography("The Beatles") is not None
  assert get_biography("Taylor Swift") is not None
  assert get_biography("Nonexistent Artist") is None
output: import requests
  
  def get_biography(artist_name):
      base_url = "https://musicbrainz.org/ws/2/artist/"
      search_url = f"https://musicbrainz.org/ws/2/artist/?query=artist:{artist_name}&fmt=json"
      
      response = requests.get(search_url)
      if response.status_code != 200:
          return None
      
      data = response.json()
      if not data['artists']:
          return None
      
      artist_id = data['artists'][0]['id']
      
      artist_url = f"{base_url}{artist_id}?inc=aliases+tags+ratings+annotation&fmt=json"
      response = requests.get(artist_url)
      if response.status_code != 200:
          return None
      
      artist_data = response.json()
      if 'annotation' in artist_data:
          return artist_data['annotation']['text']
      
      return None