input: 
  from typing import List
  
  
  def create_song_class() -> str:
      """Create the source code for a class named Song that follows the given criteria.
      The class should have two instance variables, title and artist, and three methods:
      str(), eq(), and length(). The str() method should return a formatted string with
      the title and artist. The eq() method should compare two instances of Song based
      on their title and artist. The length() method should return the length of the
      title.
      
      Example:
      for create_song_class() == "class Song:\n    def __init__(self, title, artist):\n        self.title = title\n        self.artist = artist\n\n    def __str__(self):\n        return f'Title: {self.title}\\nArtist: {self.artist}'\n\n    def __eq__(self, other):\n        return self.artist == other.artist and self.title == other.title\n\n    def length(self):\n        return len(self.title)\n"
      """
  
output:     
      return "class Song:\n    def __init__(self, title, artist):\n        self.title = title\n        self.artist = artist\n\n    def __str__(self):\n        return f'Title: {self.title}\\nArtist: {self.artist}'\n\n    def __eq__(self, other):\n        return self.artist == other.artist and self.title == other.title\n\n    def length(self):\n        return len(self.title)\n"
  