If either sub-expression is non-numeric, then both expressions are
converted (if necessary) to strings and string comparison is done.
+=item I<expr> B<E<lt>E<gt>> I<expr>
+
+=item I<expr> B<!=> I<expr>
+
+Either form can be used to test the two expressions for inequality.
+
=item B<!> I<expr>
Boolean negative of I<expr>.