# File lib/rake.rb, line 1445
1445:     def [](task_name, scopes=nil)
1446:       task_name = task_name.to_s
1447:       self.lookup(task_name, scopes) or
1448:         enhance_with_matching_rule(task_name) or
1449:         synthesize_file_task(task_name) or
1450:         fail "Don't know how to build task '#{task_name}'"
1451:     end