docs: function StartableModel(model,instance) {
      if(!model) {
          throw new Error('model is required')
      }
      if(!instance) {
          throw new Error('instance is required')
      }
      if(!(this instanceof StartableModel)) {
          return new StartableModel(model,instance,index)
      }
      this.model = model
      this.key = model.key
      this.instance= instance
      this.fn = instance[model.startable]
      if(!this.fn) {
          throw new Error('The instance of ' +
                          this.key +
                          ' does not have a method ' +
                          model.startable +
                         ' which is required for starting this service.')
      }
      this.inject = (this.fn.inject || [])
      this.hasDeps = (this.inject.length > 0)
  }