❯ curl -X 'GET' \ 
  'http://localhost:3000/v1/contract/koin/balance_of?owner=1NsQbH5AhQXgtSNg1ejpFqTi2hmCWz1eQS' \
  -H 'accept: application/json' | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    25    0    25    0     0    985      0 --:--:-- --:--:-- --:--:--  1000
{
  "value": "2391319670404"
}

❯ curl -X 'POST' \
  'http://localhost:3000/v1/contract/koin/balance_of' \                                         
  -H 'accept: application/json' \   
  -H 'Content-Type: application/json' \
  -d '{
  "owner": "1NsQbH5AhQXgtSNg1ejpFqTi2hmCWz1eQS"
}' | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    76    0    25  100    51    759   1550 --:--:-- --:--:-- --:--:--  2375
{
  "value": "2391319670404"
}