# File lib/rake/alt_system.rb, line 70
70:     def find_runnable(file)
71:       if file =~ RUNNABLE_PATTERN
72:         file
73:       else
74:         RUNNABLE_EXTS.each { |ext|
75:           if File.exist?(test = "#{file}.#{ext}")
76:             return test
77:           end
78:         }
79:         nil
80:       end
81:     end