code: def test_return_startsubstring(self):
      assert (
          substring(self.line1, -500, 0.6).wkt
          == LineString([(0, 0), (0.6, 0)]).wkt
      )
      assert (
          substring(self.line1, -1.1, 0.6, True).wkt
          == LineString([(0, 0), (1.2, 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 5 for calling the SubstringTestCase obj's underlying member method code with example usage: obj.test_return_startsubstring() without return types