code: function determineTaskList(packages, server=false) {
    if ( packages === null ) {
      return server ? conf.live_server_packages : conf.packages; 
    } else if (typeof packages === 'string'){
      return packages.split(',')
    } else {
      throw 'problem reading list of packages. It is neither empty nor a comma-separated list.'
    }
  }
docs: server argument selects packages from config for which it makes sense to start live-server.