Use of for loop in pic

[Dan Flak]

I tried using the following example directly from the book,"Document
Formatting and Typesetting on the Unix Syatem" by Narain Gehani, page
168:

#-----start file -----
.PS

h = 2.0; y = 0.5; x = 0.5; n = 10

H: line right h

L1: line up y from H.end
L2: line down y from H.end

for i = 0 to n do
{
    line right x from i/n <L1.end, L2.end>
}
.PE
#----- end file -----

What I get as an error message is:

#----- start error message -----
pic: end of file inside .PS/.PE (Not a typewriter) near line 14, file cost_bene
 context is
	.PE >>> 
 <<< /8837/
h = 2.0; y = 0.5; x = 0.5; n = 10

H: line right h

L1: line up y from H.end
L2: line down y from H.end

for i = 0 to n do
{
    line right x from i/n <L1.end, L2.end>
}
.PE
#----- end error message -----

If I comment out the for loop, things go OK. Also what does the 
<<< /8837/ mean? line 14 is the ".PE" and 'se list' shows no unusual 
characters in the text.

Any suggestions?
-- 
       Dan Flak - McCaw Cellular Communications Inc., 201 Elliot Ave W.,
    Suite 105, Seattle, Wa 98119, 206-286-4355, (usenet: thebes!mcgp1!flak)