code: def deduplicate_timeseries_dataframe(df, dt_col):
      """
      deduplicate and return a dataframe with no identical rows.
      :param df: input dataframe.
      :param dt_col: name of datetime colomn.
      """
      from bigdl.nano.utils.common import invalidInputError
  
      invalidInputError(
          dt_col in df.columns,
          f"dt_col {dt_col} can not be found in df.",
      )
      invalidInputError(
          pd.isna(df[dt_col]).sum() == 0, "There is N/A in datetime col"
      )
      res_df = df.drop_duplicates()
      return res_df
  
label_desc: Use image node_id 1 for calling a global function with example usage: deduplicate_timeseries_dataframe(df, dt_col) and returns: res_df