# File lib/autumn/tool/bin.rb, line 172
        def al_root
          require "pathname"
          dir = nil
          if ARGV.size == 1
            dir = Pathname.new(ARGV.shift)
          elsif ARGV.size > 1
            $stderr.puts "Unknown options given #{ARGV.join(" ")}"
            puts usage
            exit 1
          end
          if dir.nil? or not dir.directory?
            dir = Pathname.new(ENV["PWD"]).expand_path
            $stderr.puts "Path to autumn tree not given or invalid, using #{dir}"
          end
          Object.const_set("AL_ROOT", dir.expand_path.to_s)
          Dir.chdir(AL_ROOT)
        end