docs: def download(self, overwrite=True):
          """
          Download the zipcodes CSV file. If ``overwrite`` is set to False, the
          file won't be downloaded if it already exists.
          """
          if overwrite or not os.path.exists(self.file_path):
              _, f = tempfile.mkstemp()
              try:
                  urlretrieve(self.DOWNLOAD_URL, f)
                  extract_csv(f, self.file_path)
              finally:
                  os.remove(f)