# File lib/rake.rb, line 372
372:     def lookup(name)
373:       if @hash.has_key?(name)
374:         @hash[name]
375:       elsif ENV.has_key?(name.to_s)
376:         ENV[name.to_s]
377:       elsif ENV.has_key?(name.to_s.upcase)
378:         ENV[name.to_s.upcase]
379:       elsif @parent
380:         @parent.lookup(name)
381:       end
382:     end