code: def test_merge_key_name(self):
      tableset = TableSet(
          self.tables.values(), self.tables.keys(), key_name="foo"
      )
  
      table = tableset.merge()
  
      self.assertColumnNames(table, ["foo", "letter", "number"])
      self.assertColumnTypes(table, [Text, Text, Number])
  
file_path: agate/tests/test_tableset/test_merge.py
imports: from collections import OrderedDict
  from agate import Table, TableSet
  from agate.data_types import Number, Text
  from agate.testcase import AgateTestCase
label_desc: Use image node_id 3 for calling the TestAggregate obj's underlying member method code with example usage: obj.test_merge_key_name() without return types