code: def test_self_join(self):
      # SPARK-34319: self-join with FlatMapCoGroupsInPandas
      df = self.spark.createDataFrame([(1, 1)], ("column", "value"))
  
      row = (
          df.groupby("ColUmn")
          .cogroup(df.groupby("COLUMN"))
          .applyInPandas(lambda r, l: r + l, "column long, value long")
      )
  
      row = row.join(row).first()
  
      self.assertEqual(row.asDict(), Row(column=2, value=2).asDict())
  
imports: import unittest
  from typing import cast
  from pyspark.sql.functions import array, explode, col, lit, udf, pandas_udf, sum
  from pyspark.sql.types import ArrayType, DoubleType, LongType, StructType, StructField, YearMonthIntervalType, Row
  from pyspark.sql.window import Window
  from pyspark.errors import IllegalArgumentException, PythonException
  from pyspark.testing.sqlutils import ReusedSQLTestCase, have_pandas, have_pyarrow, pandas_requirement_message, pyarrow_requirement_message
  from pyspark.testing.utils import QuietTest
label_desc: Use image node_id 35 for calling the CogroupedApplyInPandasTestsMixin obj's underlying member method code with example usage: obj.test_self_join() without return types