code: def toDtype(self):
      str_fields1 = ["str" for i in self.string_cols1]
      int_fields1 = ["int" for i in self.int_cols1]
      str_fields2 = ["str" for i in self.string_cols2]
      int_fields2 = ["int" for i in self.int_cols2]
      bool_fields1 = ["bool" for i in self.bool_cols1]
      int_fields3 = ["int" for i in self.int_cols3]
      str_fields3 = ["str" for i in self.string_cols3]
      int_fields4 = ["int" for i in self.int_cols4]
      bool_fields2 = ["bool" for i in self.bool_cols2]
      int_fields5 = ["int" for i in self.int_cols5]
      bool_fields3 = ["bool" for i in self.bool_cols3]
      float_fields = ["float" for i in self.float_cols]
      return (
          str_fields1
          + int_fields1
          + str_fields2
          + int_fields2
          + bool_fields1
          + int_fields3
          + str_fields3
          + int_fields4
          + bool_fields2
          + int_fields5
          + bool_fields3
          + float_fields
      )
  
file_path: BigDL/python/friesian/example/wnd/recsys2021/valid_to_parquet.py
imports: import os
  from time import time
  from argparse import ArgumentParser
  from bigdl.orca import init_orca_context, stop_orca_context
  from bigdl.friesian.feature import FeatureTable
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 3 for calling the RecsysSchema obj's underlying member method code with example usage: obj.toDtype() and returns: unknown