code: def test_append_sorts(self, sort):
      df1 = DataFrame({"a": [1, 2], "b": [1, 2]}, columns=["b", "a"])
      df2 = DataFrame({"a": [1, 2], "c": [3, 4]}, index=[2, 3])
  
      result = df1._append(df2, sort=sort)
  
      # for None / True
      expected = DataFrame(
          {
              "b": [1, 2, None, None],
              "a": [1, 2, 1, 2],
              "c": [None, None, 3, 4],
          },
          columns=["a", "b", "c"],
      )
      if sort is False:
          expected = expected[["b", "a", "c"]]
      tm.assert_frame_equal(result, expected)
  
imports: import datetime
  from itertools import combinations
  import dateutil
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, Series, Timestamp, concat, isna
  import pandas._testing
label_desc: Use image node_id 7 for calling the TestAppend obj's underlying member method code with example usage: obj.test_append_sorts(sort) without return types