So far we have only made use of TEMPLATE level parameters in this contract. GLOBAL parameters are defined outside of contracts so we will not be dealing with them here, but INSTANCE parameters are worth looking at.
Exercise
In this exercise, you need to implement the application of interest once a month with a payment date that the customer can define. This should be an optional parameter. You should then instruct the movement of funds from the ACCRUED address to the DEFAULT address on the selected date.
We introduce two helper functions here to round values appropriately for application (2 decimal places) and accrual (5 decimal places) of interest.