`undefined<-` <- function(x, codes = numeric(), value) {
if(length(codes) > 0)
x[ x %in% codes] <- NA
x[is.na(x)] <- value
x
}
`undefined<-` <- function(x, codes = numeric(), value) {
if(length(codes) > 0)
x[ x %in% codes] <- NA
x[is.na(x)] <- value
x
}