Cannot find the function httpd_util:header as described by documents

[George Xu]

The erlang documents describes a function named header in the module of 
http_util (http://erlang.org/doc/man/httpd_util.html)

header(StatusCode,PersistentConn)
header(StatusCode,Date)
header(StatusCode,MimeType,Date)
header(StatusCode,MimeType,PersistentConn,Date) -> HTTPHeader

when I want to use them to fill my http response header, error accoured:

7> httpd_util:header(403, true).
** exception error: undefined function httpd_util:header/2

I looked the R13B01, R13A and R12B-5's source code and it really do not 
there!!!

Which version of inets has this function? 

George Fly