-

# File activesupport/lib/active_support/duration.rb, line 52
      def -(other)
        if Duration === other
          seconds   = value - other.parts[:seconds]
          new_parts = other.parts.map { |part, other_value| [part, -other_value] }.to_h
          new_parts = new_parts.merge(seconds: seconds)
          new_value = value - other.value

          Duration.new(new_value, new_parts)
        else
          calculate(:-, other)
        end
      end