input: Write a function that creates a class Song in Python with two instance variables, title and artist, and three methods, __str__(), __eq__(), and length().
  
  
  class Song:
      def __init__(self, title, artist):
          self.title = title
          self.artist = artist
    
      def __str__(self):
          return f'Title: {self.title}\nArtist: {self.artist}'
      
      def __eq__(self, other):
          return self.artist == other.artist and self.title == other.title
  
      def length(self):
          return len(self.title)
  
  # Test cases
  assert str(Song("Bohemian Rhapsody", "Queen")) == "Title: Bohemian Rhapsody\nArtist: Queen"
  assert Song("Bohemian Rhapsody", "Queen") == Song("Bohemian Rhapsody", "Queen")
  assert Song("Bohemian Rhapsody", "Queen") != Song("Stairway to Heaven", "Led Zeppelin")
  assert Song("Bohemian Rhapsody", "Queen").length() == len("Bohemian Rhapsody")
  assert Song("", "Unknown Artist").length() == 0
  
output: def __init__(self, title, artist):
      self.title = title
      self.artist = artist
  
  def __str__(self):
      return f'Title: {self.title}\nArtist: {self.artist}'
  
  def __eq__(self, other):
      return self.artist == other.artist and self.title == other.title
  
  def length(self):
      return len(self.title)