my $key = $institution
          && ($valid_institution{lc($institution)} || "other")
          || "unaffiliated";

##</code><code>##

## I'm promising that the true branch here can NEVER EVER EVER
## return a false value, which would have caused the
## false branch to be erroneously executed.  If you're
## updating this code, please continue to maintain
## this precondition, which I have placed precariously
## and needlessly in this code. Have a nice day.

##</code><code>##

my $key = $institution
          ? ($valid_institution{lc($institution)} || "other")
          : "unaffiliated";