# File lib/rake/task_manager.rb, line 167
167:     def lookup(task_name, initial_scope=nil)
168:       initial_scope ||= @scope
169:       task_name = task_name.to_s
170:       if task_name =~ /^rake:/
171:         scopes = []
172:         task_name = task_name.sub(/^rake:/, '')
173:       elsif task_name =~ /^(\^+)/
174:         scopes = initial_scope[0, initial_scope.size - $1.size]
175:         task_name = task_name.sub(/^(\^+)/, '')
176:       else
177:         scopes = initial_scope
178:       end
179:       lookup_in_scope(task_name, scopes)
180:     end