# File lib/rake.rb, line 391
391:     def lookup(name)
392:       if @hash.has_key?(name)
393:         @hash[name]
394:       elsif ENV.has_key?(name.to_s)
395:         ENV[name.to_s]
396:       elsif ENV.has_key?(name.to_s.upcase)
397:         ENV[name.to_s.upcase]
398:       elsif @parent
399:         @parent.lookup(name)
400:       end
401:     end