code: function (connectionName, cb) {
  
        function shutdownConnection(id) {
          if (connections[id].client) {
            connections[id].client.shutdown();
          }
          delete connections[id];
        }
  
        if (typeof connectionName == 'function') {
          cb = connectionName;
          connectionName = null;
        }
  
        // shutdown connections
        if (connectionName) {
          shutdownConnection(connectionName);
        }
        else {
          Object.keys(connections).forEach(function (conn) {
            shutdownConnection(conn);
          });
        }
  
        cb();
      }
docs: Teardown
  
  Removes the connection object from the registry.
  
  @param {String} connectionName
  @param {Function} cb