text: 
  exports.up = function (knex) {
    return knex.schema
      .createTable('users', tbl => {
        tbl.increments('id');
        tbl.string('username', 255)
          .notNullable()
          .unique()
          .index();
        tbl.string('password', 255)
          .notNullable();
      });
  };
  
  exports.down = function (knex) {
    return knex.schema.dropTableIfExists('users');
  };
  