Flarum\Database\Migration::addColumns PHP Method

    public static function addColumns($tableName, array $columnDefinitions)
    {
        return ['up' => function (Builder $schema) use($tableName, $columnDefinitions) {
            $schema->table($tableName, function (Blueprint $table) use($columnDefinitions) {
                foreach ($columnDefinitions as $columnName => $options) {
                    $type = array_shift($options);
                    $table->addColumn($type, $columnName, $options);
                }
            });
        }, 'down' => function (Builder $schema) use($tableName, $columnDefinitions) {
            $schema->table($tableName, function (Blueprint $table) use($columnDefinitions) {
                $table->dropColumn(array_keys($columnDefinitions));
            });
        }];
    }

<?php

/*
 * This file is part of Flarum.
 *
 * (c) Toby Zerner <*****@*****.**>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
use Flarum\Database\Migration;
return Migration::addColumns('users', ['twitter_id' => ['string', 'length' => 255, 'nullable' => true]]);