code: function getService (name) {
      // get service from global register
      var service = getGlobal().services[name]
      // require service to be defined
      assert(defined(service), `service ${name} not defined`)
      // return service
      return service
  }
docs: @function getService
  
  get a service by name - throws error if name not defined
  
  @param {string} name
  
  @returns {ImmutableCoreService}
  
  @throws {Error}