input: Write a function to retrieve song lyrics from azlyrics.com.
  assert 'Because I\'m happy' in get_lyrics('Happy Pharrell Williams')
  assert 'Just gonna stand there and watch me burn' in get_lyrics('Love The Way You Lie Eminem')
  assert 'Hey, I just met you, and this is crazy' in get_lyrics('Call Me Maybe Carly Rae Jepsen')
output: import requests
  from bs4 import BeautifulSoup
  import re
  
  def get_lyrics(song_name):
      base_url = "https://www.azlyrics.com/lyrics/"
      
      # Format song_name into the format used in azlyrics URL
      song_name_parts = song_name.lower().split()
      artist = song_name_parts[-2]
      song = song_name_parts[0]
      for i in range(1, len(song_name_parts)-2):
          song += song_name_parts[i]
      
      url = f"{base_url}{artist}/{song}.html"
      
      # Request the page
      response = requests.get(url)
      response.raise_for_status()
      
      # Parse the HTML
      soup = BeautifulSoup(response.text, 'html.parser')
      
      # Lyrics are within a div that follows a comment with text "start of lyrics"
      lyrics_div = soup.find_all("div", class_=None)[1]  # azlyrics has unique div structure
      lyrics = lyrics_div.get_text().strip()
      
      return lyrics