code: function projectProp(val,prop,obj) {
      var props = {};
      props[prop.pname] = obj[prop.pname]();
      children.forEach(function(ch) {
          ch.send({
              command:'update',
              id:obj.id(),
              props: props,
          });
      });
  }
docs: children.push(cp.fork('demos/projection/slave.js'));