code: func (n *routeNode) findChild(nn *routeNode) *routeNode {
  	for _, c := range n.children {
  		if c.path == nn.path {
  			// same node
  			return c
  		}
  	}
  	return nil
  }
docs: // findChild finds a child node that matches the given node
  // It returns nil if no node found. This is to see if
  // we already have a similar node registered