Proper formated instrument key

WHAT IS PROPER FORMAT FOR THE INSTRUMENT KEY. I AM CONFUCED.

# hISTORICAL DATA

# create an instance of the API class
api_instance = upstox_client.HistoryApi()
instrument_key = 'NSE_EQ|INE081A01020' # str | 
interval = '1minute' # str | 
to_date = '2023-1-11' # str | 
api_version = api # str | API Version Header

try:
    # Historical candle data
    api_response = api_instance.get_historical_candle_data(instrument_key, interval, to_date, api_version)
    pprint(api_response)
except ApiException as e:
    print("Exception when calling HistoryApi->get_historical_candle_data: %s\n" % e)

THIS IS MY CODE AND IT THROW SOME ERROR
HTTP response body: b’{“status”:“error”,“errors”:[{“errorCode”:“UDAPI100038”,“message”:null,“propertyPath”:null,“invalidValue”:null,“error_code”:“UDAPI100038”,“property_path”:null,“invalid_value”:null}]}’

Kindly adjust the ‘to_date’ parameter to follow the YYYY-MM-DD format as outlined in the document at the following link: Upstox API Documentation - Get Historical Candle Data.

For example, you can use ‘2023-12-18’ for the ‘to_date’ parameter, which should be acceptable.