# File lib/ruote/exp/fe_reserve.rb, line 48
    def apply

      return reply_to_parent(h.applied_workitem) if tree_children.empty?

      h.mutex_name = attribute(:mutex) || attribute_text
      h.mutex_name = 'reserve' if h.mutex_name.strip == ''

      raise(
        ArgumentError.new("can't bind reserve mutex at engine level")
      ) if h.mutex_name.match(/^\/\//)

      set_mutex
    end