code: def write_shas_to_shastore(sha_dict):
      
      if sys.version_info[0] < 3:
          fn_open = open
      else:
          fn_open = io.open
      with fn_open(".shastore", "w") as fh:
          fh.write("---\n")
          fh.write('sake version: {}\n'.format(constants.VERSION))
          if sha_dict:
              fh.write(yaml.dump(sha_dict))
          fh.write("...")
docs: Writes a sha1 dictionary stored in memory to
      the .shastore file