```ruby
# frozen_string_literal: true

module Mnemosyne
  module VERSION
    MAJOR = 1
    MINOR = 12
    PATCH = 0
    STAGE = nil

    STRING = [MAJOR, MINOR, PATCH, STAGE].reject(&:nil?).join('.')

    def self.to_s
      STRING
    end
  end
end
```

Use compact instead of reject(&:nil?)
user
```ruby
# frozen_string_literal: true

module Mnemosyne
  module VERSION
    MAJOR = 1
    MINOR = 12
    PATCH = 0
    STAGE = nil

    STRING = [MAJOR, MINOR, PATCH, STAGE].compact.join('.')

    def self.to_s
      STRING
    end
  end
end
```
assistant