What Terraform feature is shown in the example below?

1. resource "aws_security_group" "example" {

2. name = "sg-app-web-01"

3. dynamic "ingress" {

4. for_each = var.service_ports

5. content {

6. from_port = ingress.value

7. to_port = ingress.value

8. protocol = "tcp"

9. }

10. }

11. }