code: def test_index(self):
      self.assertEqual(self.table.columns["one"].index, 0)
      self.assertEqual(self.table.columns["two"].index, 1)
      self.assertEqual(self.table.columns["three"].index, 2)
  
imports: import pickle
  import unittest
  from decimal import Decimal
  from agate import Table
  from agate.data_types import Number, Text
label_desc: Use image node_id 2 for calling the TestColumn obj's underlying member method code with example usage: obj.test_index() without return types