In terraform, say you have a declared (and assigned values via the default argument) a variabled called "amis", as
follows:

variable "amis" {
  default = {
    "us-east-1" = "ami-b374d5a5"
    "us-west-2" = "ami-4b32be2b"
  }
}

And you have declared region variable as follows:

variable "region" {}

Complete the configure code block below to assign the right AMI to your EC2 resource, based on the "region" input variable give at "terraform apply" runtime:

resource "aws_instance" "example" {
ami = [...]
instance_type = "t2.micro"
}

In terraform, say you have a declared (and assigned values via the default argument) a variabled called "amis", as
follows:

variable "amis" {
  default = {
    "us-east-1" = "ami-b374d5a5"
    "us-west-2" = "ami-4b32be2b"
  }
}

And you have declared region variable as follows:

variable "region" {}

Complete the configure code block below to assign the right AMI to your EC2 resource, based on the "region" input variable give at "terraform apply" runtime:

resource "aws_instance" "example" {
ami = [...]
instance_type = "t2.micro"
}

"${lookup(var.amis, var.region)}"

^^ note use of built-in lookup function that takes a map argument and a key argument and returns the value for the key
^^^ note the outer double-quote enclosing to denote a returned string value
^^^^ note the inner ${} enclosing to denote that the value is derived/computed