=over 4
-=item o
+=item *
a subroutine or method call
-=item o
+=item *
a regular expression match, i.e. C</REGEX/> or C<$foo =~ /REGEX/>,
or a negated regular expression match C<$foo !~ /REGEX/>.
-=item o
+=item *
a comparison such as C<$_ E<lt> 10> or C<$x eq "abc">
(or of course C<$_ ~~ $c>)
-=item o
+=item *
C<defined(...)>, C<exists(...)>, or C<eof(...)>
-=item o
+=item *
A negated expression C<!(...)> or C<not (...)>, or a logical
exclusive-or C<(...) xor (...)>.