code: def _linear_impute_timeseries_dataframe(df, dt_col):
      res_df = df.copy()
      res_df[dt_col] = 0
      res_df = res_df.interpolate(
          method="linear", axis=0, limit_direction="both"
      )
      res_df[dt_col] = df[dt_col]
      return res_df
  
imports: import pandas
label_desc: Use image node_id 4 for calling a global function with example usage: _linear_impute_timeseries_dataframe(df, dt_col) and returns: res_df