# File lib/rake/task_manager.rb, line 192
    def lookup(task_name, initial_scope=nil)
      initial_scope ||= @scope
      task_name = task_name.to_s
      if task_name =~ /^rake:/
        scopes = Scope.make
        task_name = task_name.sub(/^rake:/, "")
      elsif task_name =~ /^(\^+)/
        scopes = initial_scope.trim($1.size)
        task_name = task_name.sub(/^(\^+)/, "")
      else
        scopes = initial_scope
      end
      lookup_in_scope(task_name, scopes)
    end