curl --location --request GET '/tenants//appointments//staffs/next_availability?start_date&end_date'
{
"today": "2019-08-24T14:15:22Z",
"appointment_catagory_id": 0,
"appointment_catagory_pri_name": "string",
"appointment_catagory_sec_name": "string",
"spot_duration_in_min": 0,
"Staffs": [
{
"staff_id": 0,
"next_available_spot": "2019-08-24T14:15:22Z"
}
]
}