code: function api_decorate() {
      var args = Norma('property:s value:.', arguments)
  
      var property = args.property
      Assert(property[0] !== '_', 'property cannot start with _')
      Assert(
        private$.decorations[property] === undefined,
        'seneca is already decorated with the property: ' + property
      )
      Assert(
        root$[property] === undefined,
        'cannot override a core seneca property: ' + property
      )
  
      root$[property] = private$.decorations[property] = args.value
    }
docs: Inspired by https://github.com/hapijs/hapi/blob/master/lib/plugin.js decorate TODO: convert to seneca errors