input: Write a function that creates a Python class `Song` with two instance variables, `title` and `artist`, and three methods, `__str__()`, `__eq__()`, and `length()`. The `__str__()` method should return a string formatted as "Title: {title}\nArtist: {artist}". The `__eq__()` method should return `True` if the `artist` and `title` of two `Song` objects are equal, and `False` otherwise. The `length()` method should return the length of the `title`. If the class is implemented correctly, the following test cases should pass:
  
  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() == 15
  assert Song("A", "B").length() == 1
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)