Unnecessary code in "Parsing with OCamllex and Menhir" ?

[benjub]

In https://dev.realworldocaml.org/parsing-with-ocamllex-and-menhir.html, the book defines a function

open Lexing

let next_line lexbuf =
  let pos = lexbuf.lex_curr_p in
  lexbuf.lex_curr_p <-
    { pos with pos_bol = pos.pos_cnum;
               pos_lnum = pos.pos_lnum + 1
    }

but the Lexing module already contains a function new_line which is nearly identical (except that it also handles the case when positions are not tracked). Is there a particular reason to define a new function ?