code: func (l *LARS) Register404(notFound ...Handler) {
  
  	chain := make(HandlersChain, len(notFound))
  
  	for i, h := range notFound {
  		chain[i] = l.wrapHandler(h)
  	}
  
  	l.http404 = chain
  }
docs: // Register404 alows for overriding of the not found handler function.
  // NOTE: this is run after not finding a route even after redirecting with the trailing slash