region name followed by abc

region_abc.tf

variable "region" {
    type = map(string)
    default = {
        "development" = "us-west-2"
        "qa"          = "us-east-2"
        "staging"     = "us-east-1"
        "production"  = "ca-central-1"
    }
}

module "vpc" {

    # omitted arguments for brevity

    azs = [
        "${lookup(var.region, var.environment)}a",
        "${lookup(var.region, var.environment)}b",
        "${lookup(var.region, var.environment)}c",
    ]
}