code: def kms_key_arn(kms_client, alias):
    
    try:
      response = kms_client.describe_key(KeyId=alias)
      key_arn = response["KeyMetadata"]["Arn"]
    except ClientError as error:
      raise RuntimeError("Failed to obtain key arn for alias {}, error: {}".format(alias, error.response["Error"]["Message"]))
  
    return key_arn
docs: Obtain the full key arn based on the key alias provided
    Args:
      kms_client (boto3 kms client object): Instantiated kms client object. Usually created through create_aws_clients.
      alias (string): alias of key, example alias/proto0-evs-drm.
  
    Returns:
      string of the full key arn