=over

=item wantarray

Returns TRUE if the context of the currently executing subroutine is
looking for a list value.  Returns FALSE if the context is looking
for a scalar.  Returns the undefined value if the context is looking
for no value (void context).

    return unless defined wantarray;	# don't bother doing more
    my @a = complex_calculation();
    return wantarray ? @a : "@a";

=back