curl --request POST \
  --url https://api.example.com/v1/accounts/balance/currency \
  --header 'Content-Type: application/json' \
  --data '
{
  "customer_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "currency": "<string>"
}
'

{
  "balance": 123,
  "currency": "<string>"
}