new_contents: import os
  from config import PACKAGE_CACHE_DIR
  
  def list_packages():
      pkgs = []
      for (dirpath, dirnames, filenames) in os.walk(os.path.expanduser(PACKAGE_CACHE_DIR)):
          pkgs.extend(dirnames)
          break
      return pkgs
  
  def list_distributions(pkg_name):
      dists = []
      for (dirpath, dirnames, filenames) in os.walk(os.path.join(os.path.expanduser(PACKAGE_CACHE_DIR), pkg_name)):
          dists.extend(filenames)
          break
      return dists
  
  def get_distribution(pkg, dist):
      return open(os.path.join(os.path.expanduser(PACKAGE_CACHE_DIR), pkg, dist), 'r')
subject: Add cache.py