code: def test_return_z_coord_issue1699(self):
      line_z = LineString([(0, 0, 0), (2, 0, 0)])
      assert (
          substring(line_z, 0, 0.5, True).wkt
          == LineString([(0, 0, 0), (1, 0, 0)]).wkt
      )
      assert (
          substring(line_z, 0.5, 0, True).wkt
          == LineString([(1, 0, 0), (0, 0, 0)]).wkt
      )
  
imports: import json
  import unittest
  import pytest
  from shapely.errors import GeometryTypeError
  from shapely.geometry import LineString, Point, shape
  from shapely.ops import substring
label_desc: Use image node_id 15 for calling the SubstringTestCase obj's underlying member method code with example usage: obj.test_return_z_coord_issue1699() without return types