DESCRIPTION By default will format all values that are regarded as true by Perl with "yes", and all false values as "no". Undef will be left undef. The true string and false string can be set using the formatter arguments true_str and false_str, or you can choose from a set of predefined styles. FORMATTER ARGUMENTS true_str => str false_str => str style => str (default: yes_no) Can be: yes_no, Y_N, true_false, T_F, 1_0, on_off.