code: func (p Standard) Verify(ad *AuthenticatedRequest) bool {
  	if ad == nil {
  		return false
  	}
  
  	// Standard token generation returns no error.
  	token, _ := p.Token(ad.Request)
  	if len(ad.Token) != len(token) {
  		return false
  	}
  
  	return hmac.Equal(token, ad.Token)
  }
docs: // Verify determines whether an authenticated request is valid.