-

# File activesupport/lib/active_support/duration.rb, line 53
      def -(other)
        if Duration === other
          seconds   = value - other._parts.fetch(:seconds, 0)
          new_parts = other._parts.transform_values(&:-@)
          new_parts = new_parts.merge(seconds: seconds)
          new_value = value - other.value

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