input: Write a function to create a Python class named Song with two instance variables, title and artist, and three methods, str(), eq(), and length(). The str() method should return a string in the format 'Title: {self.title}\nArtist: {self.artist}'. The eq() method should check if two Song instances have the same title and artist, and return True if they do, otherwise False. The length() method should return the length of the title.
  
  assert Song("Lose Yourself", "Eminem").__str__()=='Title: Lose Yourself\nArtist: Eminem'
  assert Song("Lose Yourself", "Eminem").__eq__(Song("Lose Yourself", "Eminem"))==True
  assert Song("Lose Yourself", "Eminem").__eq__(Song("Not Afraid", "Eminem"))==False
  assert Song("Lose Yourself", "Eminem").length()==12
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)