code: def test_face_distance_empty_lists(self):
      img = api.load_image_file(
          os.path.join(
              os.path.dirname(__file__), "test_images", "biden.jpg"
          )
      )
      face_encoding = api.face_encodings(img)[0]
  
      # empty python list
      faces_to_compare = []
  
      distance_results = api.face_distance(
          faces_to_compare, face_encoding
      )
      self.assertEqual(type(distance_results), np.ndarray)
      self.assertEqual(len(distance_results), 0)
  
      # empty numpy list
      faces_to_compare = np.array([])
  
      distance_results = api.face_distance(
          faces_to_compare, face_encoding
      )
      self.assertEqual(type(distance_results), np.ndarray)
      self.assertEqual(len(distance_results), 0)
  
imports: import unittest
  import os
  import numpy
  from click.testing import CliRunner
  from face_recognition import api
  from face_recognition import face_recognition_cli
  from face_recognition import face_detection_cli
label_desc: Use image node_id 18 for calling the Test_face_recognition obj's underlying member method code with example usage: obj.test_face_distance_empty_lists() without return types