produces plots that shed some light on the mortgages discussed in the first plotwhich was produced by invocations of plotpaymentssimply plots each payment of each mortgage against time the box containing the key appears where it does because of the value supplied to the keyword argument loc used in the call to pylab legend when loc is bound to 'bestthe location is chosen automatically this plot makes it clear how the monthly payments vary (or don'tover timebut doesn' shed much light on the relative costs of each kind of mortgage the next plot was produced by invocations of plottotpd it sheds some light on the cost of each kind of mortgage by plotting the cumulative costs that have been incurred at the start of each month the entire plot is on the leftand an enlargement of the left part of the plot is on the right the next two plots show the remaining debt (on the leftand the total net cost of having the mortgage (on the right