def loanpayment(amount, rate, npmts):
return float(amount) / pvannuity(rate, npmts)<EOL>
Amount of a constant loan payment.

Parameters
----------
amount : float
    amount of loan
rate : float
    interest rate for the given payment, i.e., monthly
    interest if the loan is to be paid off monthly.
npmts : int
    number of payments to be made.

Returns
-------
out : float
    amount to be paid each period.