input: Write a python function to convert a list of song titles to lowercase.
  assert convert_to_lowercase(["My Heart Will Go On","We Are The Champions","Thriller"]) == ["my heart will go on", "we are the champions", "thriller"]
  assert convert_to_lowercase(["Billie Jean","Purple Rain","The Show Must Go On"]) == ["billie jean", "purple rain", "the show must go on"]
  assert convert_to_lowercase(["Eye Of The Tiger","Money For Nothing","Bohemian Rhapsody"]) == ["eye of the tiger", "money for nothing", "bohemian rhapsody"]
output: def convert_to_lowercase(song_titles):
      return [title.lower() for title in song_titles]