[BASH] hash lookup

#!/bin/bash
set -e

env='prod'
team='common'
svc='adm'

declare -A IDS
IDS=(
          # prod
          ['prod']='1' 
          ['prod/auth/flow']='2'  
          ['prod/auth/account']='2' 
          ['prod/common/adm']='3'  
          # staging
          ['staging']='4'
)
# Magic is here.
ID=${IDS["${env}"]}
ID=${IDS["${env}/${team}"]:-${ID}}
ID=${IDS["${env}/${team}/${svc}"]:-${ID}}

echo "$ID"