text: import unittest
  from pyalink.alink import *
  import numpy as np
  import pandas as pd
  class TestLookupStreamOp(unittest.TestCase):
      def test_lookupstreamop(self):
  
          data_df = pd.DataFrame([
              ["10", 2.0],
              ["1", 2.0], 
              ["-3", 2.0], 
              ["5", 1.0]
          ])
          inOp = StreamOperator.fromDataframe(data_df, schemaStr='f0 string, f1 double')
          
          model_df = pd.DataFrame([
              ["1", "value1"], 
              ["2", "value2"], 
              ["5", "value5"]
          ])
          
          modelOp = BatchOperator.fromDataframe(model_df, schemaStr="key_col string, value_col string")
          
          LookupStreamOp(modelOp)\
              .setMapKeyCols(["key_col"])\
              .setMapValueCols(["value_col"]) \
              .setSelectedCols(["f0"])\
              .linkFrom(inOp)\
              .print()
          
          StreamOperator.execute()
          pass