code: def test_convert_to_output_format(self):
      out = convert_to_output_format({"p1": 1, "p2": "a"})
      expected_out = 'p1_1__p2_"a"'
      self.assertEqual(out, expected_out)
  
      out = convert_to_output_format({"list": [1, 2, 4]})
      expected_out = "list_[1, 2, 4]"
      self.assertEqual(out, expected_out)
  
      out = convert_to_output_format({"list": ["a", "b", "c"]})
      expected_out = "list_['a', 'b', 'c']"
      self.assertEqual(out, expected_out)
  
imports: from unittest import TestCase
  from tsfresh.utilities.string_manipulation import convert_to_output_format
label_desc: Use image node_id 1 for calling the StringUtilities obj's underlying member method code with example usage: obj.test_convert_to_output_format() without return types