code: def get_path(download_name, filename='', test_exists=True):
      
      assert '/' not in download_name, "Invalid download: %s" % download_name
      path = join(get_downloads_dir(), download_name, filename)
      if test_exists and not exists(path):
          raise RuntimeError(
              "Missing MHCflurry downloadable file: %s. "
              "To download this data, run:\n\tmhcflurry-downloads fetch %s\n"
              "in a shell."
              % (quote(path), download_name))
      return path
docs: Get the local path to a file in a MHCflurry download
  
      Parameters
      -----------
      download_name : string
  
      filename : string
          Relative path within the download to the file of interest
  
      test_exists : boolean
          If True (default) throw an error telling the user how to download the
          data if the file does not exist
  
      Returns
      -----------
      string giving local absolute path