code: def test_expand_x(self):
      # Arrange
      im = hopper()
      orig_size = im.size
      xmargin = 5
  
      # Act
      im = im._expand(xmargin)
  
      # Assert
      assert im.size[0] == orig_size[0] + 2 * xmargin
      assert im.size[1] == orig_size[1] + 2 * xmargin
  
imports: import io
  import os
  import shutil
  import sys
  import tempfile
  import pytest
  from PIL import Image, ImageDraw, ImagePalette, UnidentifiedImageError
  from .helper import assert_image_equal, assert_image_equal_tofile, assert_image_similar_tofile, assert_not_all_same, hopper, is_win32, mark_if_feature_version, skip_unless_feature
label_desc: Use image node_id 18 for calling the TestImage obj's underlying member method code with example usage: obj.test_expand_x() without return types