In terraform, say you declared input variable "region", using following block in your *.tf config file:

variable "region" {
   default = "us-west-2" 
}

how do you access the value of this variable in the following *.tf code block:
provider "aws" {
access_key = "AKIA98298ADFDDRDSFDFSF"
secret_key = "_adofijoeairjdsfDDF(*Fjij"
region = [...]
}

In terraform, say you declared input variable "region", using following block in your *.tf config file:

variable "region" {
   default = "us-west-2" 
}

how do you access the value of this variable in the following *.tf code block:
provider "aws" {
access_key = "AKIA98298ADFDDRDSFDFSF"
secret_key = "_adofijoeairjdsfDDF(*Fjij"
region = [...]
}

"${var.region}"

^^ Note the use of the var syntax
^^^ note the outer enclosure in double quotes to mean derived value is string
^^^^note the inner enclosure in ${} to mean that this value is derived.