code: func (r *ssrf) Match(n ast.Node, c *gosec.Context) (*gosec.Issue, error) {
  	// Call expression is using http package directly
  	if node := r.ContainsCallExpr(n, c, false); node != nil {
  		if r.ResolveVar(node, c) {
  			return gosec.NewIssue(c, n, r.ID(), r.What, r.Severity, r.Confidence), nil
  		}
  	}
  	return nil, nil
  }
docs: // Match inspects AST nodes to determine if certain net/http methods are called with variable input