new_contents: """Deletes old sessions to clear up space."""
  
  import datetime
  import os
  import sys
  import time
  
  
  def get_files(path):
      """Returns the absolute paths of all files under a path."""
      for walk_information in os.walk("data/sessions/data/container_file/"):
          directory_name, _, file_names = walk_information
          for file_name in file_names:
              full_path = os.path.join(directory_name, file_name)
              yield full_path
  
  
  def sizeof_fmt(num, suffix="B"):
      for unit in ["","Ki","Mi","Gi","Ti","Pi","Ei","Zi"]:
          if abs(num) < 1024.0:
              return "%3.1f%s%s" % (num, unit, suffix)
          num /= 1024.0
      return "%.1f%s%s" % (num, "Yi", suffix)
  
  
  def main():
      """Main."""
      sessions_path = "data/sessions/data/container_file/"
      days = 7
      cutoff = datetime.datetime.now() - datetime.timedelta(days=days)
      print("Calculating size of files older than {} days...".format(days))
      bytes_count = 0
  
      for file_path in get_files(sessions_path):
          stat = os.stat(file_path)
          if datetime.datetime.fromtimestamp(stat.st_mtime) < cutoff:
              bytes_count += stat.st_size
      print("Files older than {} days comprise {}".format(days, sizeof_fmt(bytes_count)))
  
      wait_seconds = 5
      print("Cleaning in {} seconds...".format(wait_seconds))
      time.sleep(wait_seconds)
      print("Cleaning")
      for file_path in get_files(sessions_path):
          stat = os.stat(file_path)
          if datetime.datetime.fromtimestamp(stat.st_mtime) < cutoff:
              os.unlink(file_path)
  
  
  if __name__ == "__main__":
      if sys.version_info.major < 3:
          print("Please use Python 3")
          sys.exit(1)
      main()
  
subject: Add script to delete old sessions