input: Write a function to create a Python class named "Song" which includes two instance variables, title and artist, and three methods, str(), eq(), and length().
  assert Song("Bohemian Rhapsody", "Queen").__str__()=="Title: Bohemian Rhapsody\nArtist: Queen"
  assert Song("Bohemian Rhapsody", "Queen") == Song("Bohemian Rhapsody", "Queen")
  assert Song("Bohemian Rhapsody", "Queen").length()==15
  assert Song("Lose Yourself", "Eminem").__str__()=="Title: Lose Yourself\nArtist: Eminem"
  assert Song("Lose Yourself", "Eminem") == Song("Lose Yourself", "Eminem")
  assert Song("Lose Yourself", "Eminem").length()==11
output: 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.title == other.title and self.artist == other.artist
  
      def length(self):
          return len(self.title)