code: def describe(self):
      for ts_df in self.time_series:
          print(f"length of the data: {len(ts_df)}")
          print(f"timestamp index name: {ts_df.index.name}")
          print(f"number of data columns: {len(ts_df.columns)}")
          print("data columns names (the first 20): ")
          print(ts_df.columns[:20])
          print(f"number of null entries: {ts_df.isnull().sum()}")
  
file_path: merlion/ts_datasets/ts_datasets/base.py
imports: import pandas
  from typing import Tuple
label_desc: Use image node_id 5 for calling the BaseDataset obj's underlying member method code with example usage: obj.describe() without return types