code: def test_modified_precision_empty():
      for k in range(1, 5):
          n, d = modified_precision([[]], [], k)
          assert n == 0 and d == 0
          n, d = modified_precision([[]], [0], k)
          assert n == 0 and d == (k == 1)
          n, d = modified_precision([[0]], [], k)
          assert n == 0 and d == 0
          n, d = modified_precision([[]], list(range(k)), k)
          assert n == 0 and d == 1
          n, d = modified_precision([list(range(k))], [], k)
          assert n == 0 and d == 0
  
imports: import pytest
  from ignite.metrics.nlp.utils import lcs, modified_precision, ngrams
label_desc: Use image node_id 3 for calling a global function with example usage: test_modified_precision_empty() without return types