curl --request GET \
  --url https://api.slash.com/invoice/series/{invoiceSeriesId} \
  --header 'X-API-Key: <api-key>'

{
  "$entity": "invoice_series",
  "id": "<string>",
  "recurrenceRule": {
    "type": "weekly",
    "dayOfWeek": 3
  },
  "paymentTermsDays": 123,
  "invoiceTz": "<string>",
  "startDate": "2023-11-07T05:31:56Z",
  "endCondition": {
    "type": "never"
  },
  "template": {
    "lineItemsAndTotals": {
      "lineItems": [
        {
          "name": "<string>",
          "quantity": 123,
          "priceCents": 123,
          "catalogItemId": "<string>"
        }
      ],
      "discount": {
        "type": "percentage",
        "percent": 123
      },
      "tax": {
        "type": "percentage",
        "percent": 123
      }
    },
    "memo": "<string>",
    "ccEmails": [
      "<string>"
    ]
  },
  "paymentMethods": [
    {
      "method": "ach_debit",
      "config": {
        "passFeeToPayer": true
      }
    }
  ],
  "accountId": "<string>",
  "nextScheduledDate": "2023-11-07T05:31:56Z",
  "legalEntityContactId": "<string>",
  "legalEntityCustomerId": "<string>"
}