code: def download_fci_test_data(base_dir=None):
      """Download FCI test data.
  
      Download the nominal FCI test data from July 2020.
      """
      subdir = get_fci_test_data_dir(base_dir=base_dir)
      with tempfile.TemporaryDirectory() as td:
          nm = pathlib.Path(td) / "fci-test-data.tar.gz"
          utils.download_url(_fci_uncompressed_nominal, nm)
          return _unpack_tarfile_to(nm, subdir)
  
file_path: satpy/satpy/demo/fci.py
imports: import pathlib
  import tarfile
  import tempfile
  from satpy import config
  from .None import utils
label_desc: Use image node_id 1 for calling a global function with example usage: download_fci_test_data(base_dir) and returns: _unpack_tarfile_to