code: def cat_train_and_validate_df(train_df: DataFrame, val_df: DataFrame):
      """
      Concatenate train and validate dataframe
      """
      return train_df.vstack(val_df)
  
label_desc: Use image node_id 1 for calling a global function with example usage: cat_train_and_validate_df(train_df, val_df) and returns: train_df