code: def test_truncated_buffer():
      b = BytesIO()
      plt.savefig(b)
      b.seek(0)
      b2 = BytesIO(b.read(20))
      b2.seek(0)
  
      with pytest.raises(Exception):
          plt.imread(b2)
  
file_path: matplotlib/lib/matplotlib/tests/test_png.py
imports: from io import BytesIO
  from pathlib import Path
  import pytest
  from matplotlib.testing.decorators import image_comparison
  from matplotlib import cm, pyplot
label_desc: Use image node_id 3 for calling a global function with example usage: test_truncated_buffer() without return types