code: function destroy(self, connections, options, callback) {
    let connectionCount = connections.length;
    function connectionDestroyed() {
      connectionCount--;
      if (connectionCount > 0) {
        return;
      }
  
      // Zero out all connections
      self.inUseConnections = [];
      self.availableConnections = [];
      self.connectingConnections = 0;
  
      // Set state to destroyed
      stateTransition(self, DESTROYED);
      if (typeof callback === 'function') {
        callback(null, null);
      }
    }
  
    if (connectionCount === 0) {
      connectionDestroyed();
      return;
    }
  
    // Destroy all connections
    connections.forEach(conn => {
      for (var i = 0; i < events.length; i++) {
        conn.removeAllListeners(events[i]);
      }
  
      conn.destroy(options, connectionDestroyed);
    });
  }
docs: Destroy the connections