# File lib/chef/resource/conditional.rb, line 45
      def initialize(positivity, command=nil, command_opts={}, &block)
        @positivity = positivity
        case command
        when String
          @command, @command_opts = command, command_opts
          @block = nil
        when nil
          raise ArgumentError, "only_if/not_if requires either a command or a block" unless block_given?
          @command, @command_opts = nil, nil
          @block = block
        else
          raise ArgumentError, "Invalid only_if/not_if command: #{command.inspect} (#{command.class})"
        end
      end