code: def test_stringify(self):
      self.assertEqual(
          str(self.row), "<agate.MappedSequence: ('a', 'b', 'c')>"
      )
  
imports: import unittest
  from agate.mapped_sequence import MappedSequence
label_desc: Use image node_id 3 for calling the TestMappedSequence obj's underlying member method code with example usage: obj.test_stringify() without return types