Some types of objects created by CLR are by default coerced to R-typed objects. For example, ``` r library("rClr") dt1 <- clrNew("System.DateTime", year = 2015L, month = 12L, day = 10L) ``` `dt1` will be a `POSIXct` object in R. How can I call `System.DateTime.AddDays` method to the original object?