protected function writeSchemaHelp($schema) {
        // Write the command description.
        $meta = Cli::val(Cli::META, $schema, []);
        $description = Cli::val('description', $meta);

        if ($description) {
            echo implode("\n", Cli::breakLines($description, 80, false)).PHP_EOL.PHP_EOL;
        }

        unset($schema[Cli::META]);

        // Add the help.
        $schema['help'] = [
            'description' => 'Display this help.',
            'type' => 'boolean',
            'short' => '?'
        ];

        echo Cli::bold('OPTIONS').PHP_EOL;

        ksort($schema);

        $table = new Table();
        $table->setFormatOutput($this->formatOutput);

        foreach ($schema as $key => $definition) {
            $table->row();

            // Write the keys.
            $keys = "--{$key}";
            if ($shortKey = Cli::val('short', $definition, false)) {
                $keys .= ", -$shortKey";
            }
            if (Cli::val('required', $definition)) {
                $table->bold($keys);
            } else {
                $table->cell($keys);
            }

            // Write the description.
            $table->cell(Cli::val('description', $definition, ''));
        }

        $table->write();
        echo PHP_EOL;

        $args = Cli::val(Cli::ARGS, $meta, []);
        if (!empty($args)) {
            echo Cli::bold('ARGUMENTS').PHP_EOL;

            $table = new Table();
            $table->setFormatOutput($this->formatOutput);

            foreach ($args as $argName => $arg) {
                $table->row();

                if (Cli::val('required', $arg)) {
                    $table->bold($argName);
                } else {
                    $table->cell($argName);
                }

                $table->cell(Cli::val('description', $arg, ''));
            }
            $table->write();
            echo PHP_EOL;
        }
    }