# File lib/rake.rb, line 1630
1630:     def [](task_name, scopes=nil)
1631:       task_name = task_name.to_s
1632:       self.lookup(task_name, scopes) or
1633:         enhance_with_matching_rule(task_name) or
1634:         synthesize_file_task(task_name) or
1635:         fail "Don't know how to build task '#{task_name}'"
1636:     end