code: def test_valid_download_file(eld):
      """Test that single files get downloaded."""
      file = eld.get_data("little-text-file")
      assert os.path.isfile(file)
  
imports: import os
  import requests
  import pytest
  import numpy
  import rasterio
  import geopandas
  import earthpy.io
label_desc: Use image node_id 14 for calling a global function with example usage: test_valid_download_file(eld) without return types