Docstring issue in R

Question

I am unable to view the comments which are in the doctring in R, for example I have name the function earlier square and was able to view ?square and then changed function name to ab and then try to view the docstring ?ab , I am unable to do so.

rm(list=ls(all=T))
library(docstring)
ab <- function(a){
  #' @title :square function
  #' @description : print the squares of the number 
  #'from 1 to the input given
  #' @param : input number
  #' @output : provide the squares of the input range
  for(i in 1:a){
    b <- i^2
    print(b)
  }
}
?ab

I am not sure why this is happening , I would appreciate if some could help me on this