def get_charge_amount(self, request):
        raise NotImplementedError("you must implement get_charge_amount")
hash the string using sha1 and produce a base64 output
dataset/ETHPy150Open dimagi/commcare-hq/corehq/apps/accounting/payment_handlers.py/BaseStripePaymentHandler.get_charge_amount--crossover with--dataset/ETHPy150Open benadida/helios-server/helios/crypto/utils.py/hash_b64