class Mail::Multibyte::Chars

See String#<=> for more details.

'é'.mb_chars <=> 'ü'.mb_chars # => -1

that implements +to_s+:
equal or after the object on the right side of the operation. It accepts any object
Returns -1, 0, or 1, depending on whether the Chars object is to be sorted before,

def <=>(other)
  @wrapped_string <=> other.to_s
end