    # File lib/fog/core/attributes.rb, line 169
          def requires(*args)
            missing = missing_attributes(args)
            if missing.length == 1
              raise(ArgumentError, "#{missing.first} is required for this operation")
            elsif missing.any?
              raise(ArgumentError, "#{missing[0...-1].join(", ")} and #{missing[-1]} are required for this operation")
            end
          end