conversion of "simple" lists with nested list elements of more specific classes

[famuvie]

to borrow from the example in ?as.Node.list:

kingJosephs <- list(head = "Joseph I",
                    spouse = "Mary",
                    born = "1818-02-23",
                    died = "1839-08-29",
                    list(head = "Joseph II",
                         spouse = "Kathryn",
                         born = "1839-03-28",
                         died = "1865-12-19"),
                    list(head = "Helen",
                         born = "1840-17-08",
                         died = "1845-01-01")       
                   )

## Say that one of the children lists has a more specific class
class(kingJosephs[[5]]) <- c("specific_class", "list")

FromListSimple(kingJosephs, nameName = "head")
## Error in n[[fieldNm]] <- v : 
##  se intenta usar un nombre de varible de longitud cero