R Turning several functions to one object using Object Oriented Programming (S3 and S4)

I'm trying to understand how to turn functions into object oriented programming in R. So for example, how could the data and 2 functions below be turned into one object using S3 (and then S4)? (Perhaps some other simple data and functions would serve better as examples?)

data <- c(1, 2, 3)

# Function 1
adding_1 <- function(x){
  x <- x+1
}

# Function 2
subtracting_1 <- function(x){
  x <- x-1
}

And how would below functions be executed using the OOP.

data1 <- adding_1(data)
data1
data2 <- subtracting_1(data)
data2