text: 
  exports.up = function(knex) {
      return knex.schema.createTable('notifications',notifications=>{
          notifications.increments();
  
          notifications
              .integer('user_id')
              .unsigned()
              .notNullable()
              .references('id')
              .inTable('users')
              .onDelete('CASCADE') // what happens if the user is deleted
              .onUpdate('CASCADE'); // what happens if the id of the user changes
          
          notifications
              .text('subscription')
              .notNullable();
          
          notifications
              .string('type')
              .notNullable();
      })
  };
  
  exports.down = function(knex) {
      return knex.schema.dropTableIfExists('notifications');
    
  };
  