$ touch foo.pl
$ perl -we'use diagnostics; require "foo.pl"'
foo.pl did not return a true value at -e line 1 (#1)
    (F) A required (or used) file must return a true value to indicate that
    it compiled correctly and ran its initialization code correctly.  It's
    traditional to end such a file with a "1;", though any true value would
    do.  See perlfunc/require.

Uncaught exception from user code:
        foo.pl did not return a true value at -e line 1.
 at -e line 1

##</code><code>##

$ echo "a.pl did not return a true value at ./require.plx line 7." | splain
a.pl did not return a true value at ./require.plx line 7 (#1)
    (F) A required (or used) file must return a true value to indicate that
    it compiled correctly and ran its initialization code correctly.  It's
    traditional to end such a file with a "1;", though any true value would
    do.  See perlfunc/require.