Using chr in Unicode::String?

Hi again.

print "--", utf8(chr(257))->as_string, "--";

Doesn't do what I would have expected from reading the 
Unicode::String pod. The documentation uses "uchr" in the summary at 
the top, but "chr" in the main text. The hex of the output is:
2d2d012d2d

Of course, I first tried:

print "--", utf8(uchr(257))->as_string, "--";

But that yielded:

Undefined subroutine &main::uchr called at ordtest

Any thoughts on how to get chr/uchr to work?