def lookup_in_scope(name, scope)
      loop do
        tn = scope.path_with_task_name(name)
        task = @tasks[tn]
        return task if task
        break if scope.empty?
        scope = scope.tail
      end
      nil
    end
def lookup_in_scope(name, scope)
      loop do
        tn = scope.path_with_task_name(name)
        task = @tasks[tn]
        return task if task
        break if scope.empty?
        scope = scope.tail
      end
      nil
    end
Lookup the task name