code: def test_cifti2_surface():
      s = ci.Cifti2Surface()
      with pytest.raises(ci.Cifti2HeaderError):
          s.to_xml()
  
imports: import collections
  from xml.etree import ElementTree
  import numpy
  import pytest
  from nibabel import cifti2
  from nibabel.cifti2.cifti2 import Cifti2HeaderError, _float_01, _value_if_klass
  from nibabel.nifti2 import Nifti2Header
  from nibabel.tests.test_dataobj_images import TestDataobjAPI
  from nibabel.tests.test_image_api import DtypeOverrideMixin, SerializeMixin
label_desc: Use image node_id 10 for calling a global function with example usage: test_cifti2_surface() without return types