code: def test_return_startpoint(self):
      assert substring(self.line1, -500, -600).equals(Point(0, 0))
      assert substring(self.line1, -500, -500).equals(Point(0, 0))
      assert substring(self.line1, -1, -1.1, True).equals(Point(0, 0))
      assert substring(self.line1, -1.1, -1.1, True).equals(Point(0, 0))
  
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 2 for calling the SubstringTestCase obj's underlying member method code with example usage: obj.test_return_startpoint() without return types