code: def test__accept_false():
      """Check invalid prefix"""
      # Arrange
      prefix = b"something invalid"
  
      # Act
      output = DdsImagePlugin._accept(prefix)
  
      # Assert
      assert not output
  
imports: from io import BytesIO
  import pytest
  from PIL import DdsImagePlugin, Image
  from .helper import assert_image_equal, assert_image_equal_tofile, hopper
label_desc: Use image node_id 12 for calling a global function with example usage: test__accept_false() without return types