code: def test_dtw_global_constraint_destructive():
      # Issue #1029, dtw with global constraints inserts nans
      # into the cost matrix.  This is fine when the cost is computed
      # locally, but if passed by reference, it's destructive.
      # This test checks that the cost matrix is unmodified.
      C1 = np.ones((20, 20))
      C2 = np.copy(C1)
      librosa.sequence.dtw(C=C1, global_constraints=True)
      assert np.array_equal(C1, C2)
  
imports: import librosa
  import numpy
  from scipy.spatial.distance import cdist
  import pytest
  from test_core import srand
label_desc: Use image node_id 19 for calling a global function with example usage: test_dtw_global_constraint_destructive() without return types