{
"bill_no":"<<string>>", //REQUIRED
"image": "<<url>>",
"date":"<<date>>", //REQUIRED
"expense_type":enum["doctor","visit"], //REQUIRED
"contact_id":"<<string>>",
"total_cost":"<<number>>", //Required
"visit_id":"<<string>>",
"created_by": {
"id": "<<string>>",
"name": "<<string>>",
}
, //REQUIRED
}