code: func (c *Client) FirewallRule(identifier string) (*FirewallRule, error) {
  	rule := new(FirewallRule)
  	_, err := c.MakeApiRequest("GET", "/1.0/firewall_rules/"+identifier, nil, rule)
  	if err != nil {
  		return nil, err
  	}
  	return rule, err
  }
docs: // FirewallRule retrieves a detailed view of one firewall rule