#!/usr/bin/env perl

use strict;
use warnings;

my @tests = ('0', '1', '000', '101', '010', '1 * 0 = 0');

my $format = '%9s | ' x 4 . "\n";

printf $format => qw{initial boundary start/end assign};

for (@tests) {
    my ($init, $bound, $start, $assign) = ($_) x 4;
    $bound =~ s/\b0\b/1/;
    $start =~ s/^0$/1/;
    $assign = 1 if $assign == 0;
    printf $format => $init, $bound, $start, $assign; 
}