```ruby
# typed: ignore

module Vonage
  module GSM7
    CHARACTERS = "\n\f\r !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_abcdefghijklmnopqrstuvwxyz{|}~ ¡£¤¥§¿ÄÅÆÉÑÖØÜßàäåæçèéìñòöøùüΓΔΘΛΞΠΣΦΨΩ€"

    REGEXP = /\A[#{Regexp.escape(CHARACTERS)}]*\z/

    def self.encoded?(string)
      REGEXP =~ string
    end
  end
end
```

Add sorbet types to Vonage::GSM7
user
```ruby
# typed: strong

module Vonage
  module GSM7
    extend T::Sig
    CHARACTERS = "\n\f\r !\"\#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_abcdefghijklmnopqrstuvwxyz{|}~ ¡£¤¥§¿ÄÅÆÉÑÖØÜßàäåæçèéìñòöøùüΓΔΘΛΞΠΣΦΨΩ€"

    REGEXP = /\A[#{Regexp.escape(CHARACTERS)}]*\z/

    sig {params(string: T.nilable(String)).returns(T.nilable(Integer))}
    def self.encoded?(string)
      REGEXP =~ string
    end
  end
end
```
assistant