# File lib/rake.rb, line 1468
1468:     def [](task_name, scopes=nil)
1469:       task_name = task_name.to_s
1470:       self.lookup(task_name, scopes) or
1471:         enhance_with_matching_rule(task_name) or
1472:         synthesize_file_task(task_name) or
1473:         fail "Don't know how to build task '#{task_name}'"
1474:     end