Bond flow amount does not reflect day count basis and stub period and adjusted calculation period

[hangseob]

Even when the maturity date is issue date +13 month, stub or long period coupon has the same amount of coupon as other standard length period coupons.

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def _calculate_flow_amounts(self):
    """Determine the bond cash flow payment amounts without principal.
    There is no adjustment based on the adjusted payment dts."""

    self.flow_amounts = [0.0]

    for _ in self.cpn_dts[1:]:
        cpn = self.cpn / self.freq
        self.flow_amounts.append(cpn)