input: from typing import List
  
  def create_song_class() -> str:
      """Creates a class named Song with instance variables title and artist, and methods:
      str() which returns a formatted string with title and artist,
      eq(other) which checks if two Song objects are equal based on title and artist,
      and length() which returns the length of the title.
      
      The class structure should be returned as a string.
      
      >>> 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 f"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"