code: def test_no_items():
      idx = AnnoyIndex(100, "angular")
      idx.build(n_trees=10)
      idx.save("foo.idx")
      idx = AnnoyIndex(100, "angular")
      idx.load("foo.idx")
      assert idx.get_n_items() == 0
      assert (
          idx.get_nns_by_vector(
              vector=numpy.random.randn(100),
              n=50,
              include_distances=False,
          )
          == []
      )
  
imports: import random
  import numpy
  import pytest
  from annoy import AnnoyIndex
label_desc: Use image node_id 19 for calling a global function with example usage: test_no_items() without return types