code: def read_csv(csv_name, usecols=None):
      
      csv_path = os.path.join(DATA_FOLDER, csv_name)
      csv = pd.read_csv(csv_path, low_memory=False,
                        usecols=usecols, encoding="utf-8")
      return csv
docs: Returns a DataFrame from a .csv file stored in /data/raw/