docs: def letras(song):
      """
      Returns the lyrics found in letras.com for the specified mp3 file or an
      empty string if not found.
      """
      translate = {
          '&': 'a',
          URLESCAPE: '',
          ' ': '-'
      }
      artist = song.artist.lower()
      artist = normalize(artist, translate)
      title = song.title.lower()
      title = normalize(title, translate)
  
      url = 'https://www.letras.com/{}/{}/'.format(artist, title)
      soup = get_url(url)
      if not soup:
          return ''
  
      found_title = soup.select_one('div.cnt-head_title h1')
      if not found_title:
          # The site didn't find lyrics and took us to the homepage
          return ''
  
      found_title = found_title.get_text()
      found_title = re.sub(r'[\W_]+', '', found_title.lower())
      if found_title != re.sub(r'[\W_]+', '', song.title.lower()):
          # The site took us to the wrong song page
          return ''
  
      content = soup.find('article')
      if not content:
          return ''
  
      text = ''
      for br in content.find_all('br'):
          br.replace_with('\n')
  
      for p in content.find_all('p'):
          text += p.get_text() + '\n\n'
  
      return text.strip()