```ruby
# frozen_string_literal: true

namespace :users do
  desc 'Merge users with different case variations of same email'
  task merge_duplicate_users: :environment do
    require 'duplicate_user_merger'

    DuplicateUserMerger.merge!
  end
end
```

Add a task to lowercase all existing emails
user
```ruby
# frozen_string_literal: true

namespace :users do
  desc 'Merge users with different case variations of same email'
  task merge_duplicate_users: :environment do
    require 'duplicate_user_merger'

    DuplicateUserMerger.merge!
  end

  desc 'Standarize all emails in DB to lowercase'
  task lowercase_emails: :environment do
    ActiveRecord::Base.connection.execute <<-SQL.squish
      UPDATE users SET email = LOWER(email)
    SQL
  end
end
```
assistant