code: def test_decorator(self):
      df = self.data
  
      @pandas_udf(
          "id long, v int, v1 double, v2 long",
          PandasUDFType.GROUPED_MAP,
      )
      def foo(pdf):
          return pdf.assign(v1=pdf.v * pdf.id * 1.0, v2=pdf.v + pdf.id)
  
      result = df.groupby("id").apply(foo).sort("id").toPandas()
      expected = (
          df.toPandas()
          .groupby("id")
          .apply(foo.func)
          .reset_index(drop=True)
      )
      assert_frame_equal(expected, result)
  
imports: import datetime
  import unittest
  from collections import OrderedDict
  from decimal import Decimal
  from typing import cast
  from pyspark.sql import Row
  from pyspark.sql.functions import array, explode, col, lit, udf, sum, pandas_udf, PandasUDFType, window
  from pyspark.sql.types import IntegerType, DoubleType, ArrayType, BinaryType, ByteType, LongType, DecimalType, ShortType, FloatType, StringType, BooleanType, StructType, StructField, NullType, MapType, YearMonthIntervalType
  from pyspark.errors import PythonException, PySparkTypeError
  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 6 for calling the GroupedApplyInPandasTestsMixin obj's underlying member method code with example usage: obj.test_decorator() and returns: pdf