```ruby
class CreateBalancedContributors < ActiveRecord::Migration
  def change
    create_table :balanced_contributors do |t|
      t.references :user, index: true
      t.string :uri
      t.string :credit_card_uri
      t.string :bank_account_uri

      t.timestamps
    end
  end
end
```

Remove unused fields from balanced_contributors migration
user
```ruby
class CreateBalancedContributors < ActiveRecord::Migration
  def change
    create_table :balanced_contributors do |t|
      t.references :user, index: true
      t.string :uri

      t.timestamps
    end
  end
end
```
assistant