curl --request POST \
  --url https://mag3nt.com/api/ap2/mandate \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "card_id": "<string>",
  "card_token": "<string>",
  "amount": 123,
  "merchant": "<string>",
  "max_amount": 123,
  "expires_at": "2023-11-07T05:31:56Z"
}
'

{
  "mandate_id": "<string>",
  "type": "<string>",
  "contents": {},
  "merchant_signature": "<string>",
  "ttl": "<string>",
  "protocol": "<string>"
}