yield curve - Using the termstrc package in R

I am attempting to use the function estim_nss from the termstrc package in R to find the spot curve from constant maturity rates published by the Fed. I am using this package because I will need to deal with variable rate coupon bonds in the future. The function requires an object of class "couponbonds" but I cannot figure out how to create this class. I tried creating a list object with similar data but the function rejects this object with the following message:

Error in UseMethod("estim_nss") : no applicable method for 'estim_nss' applied to an object of class "list"

Any assistance would be appreciated.

Answer

It turned out to be more simple than I thought. First, be sure to replace "STARTDATE" with "ISSUEDATE" when building the list. Once the list is build simply reclassify it using the following command:

class(mybonds)="couponbonds"

That's it!