text: import unittest
  from pyalink.alink import *
  import numpy as np
  import pandas as pd
  class TestFlattenKObjectStreamOp(unittest.TestCase):
      def test_flattenkobjectstreamop(self):
  
          df_data = pd.DataFrame([
              [1,'{"rating":"[0.6]","object":"[1]"}'],
              [2,'{"rating":"[0.8,0.6]","object":"[2,3]"}'],
              [3,'{"rating":"[0.6,0.3,0.4]","object":"[1,2,3]"}']
          ])
          
          data = BatchOperator.fromDataframe(df_data, schemaStr='user bigint, rec string')
          sdata = StreamOperator.fromDataframe(df_data, schemaStr='user bigint, rec string')
          
          recList = FlattenKObjectStreamOp()\
          			.setSelectedCol("rec")\
          			.setOutputCols(["object", "rating"])\
          			.setOutputColTypes(["long", "double"])\
          			.setReservedCols(["user"])\
          			.linkFrom(sdata).print();
          StreamOperator.execute()
          pass