expense tracker data model

expenseTrackerDataModel.js

users: {
  id: "UUID",
  email: "string",
  firstName: "string",
  lastName: "string",
  group: groupId
}

groups: {
 id: "UUID",
 members: [
   ...userIds,
   ]
}
  
 expenses: {
   id: "UUID",
   associatedGroup: "groupId",
   createdBy: "userID",
   createdAtDate: "dateString",
   amount: float,
   description: "string"
 }