code: def test_iterate(self):
      it = iter(self.row)
  
      self.assertSequenceEqual(next(it), "a")
      self.assertSequenceEqual(next(it), "b")
      self.assertSequenceEqual(next(it), "c")
  
      with self.assertRaises(StopIteration):
          next(it)
  
imports: import unittest
  from agate.mapped_sequence import MappedSequence
label_desc: Use image node_id 21 for calling the TestMappedSequence obj's underlying member method code with example usage: obj.test_iterate() without return types