Revenue Tracking System

Design a system to track revenues. Implement the following functions: add(revenue: int) -> int: Add a new revenue and return a new revenue ID. add(revenue: int, id: int): Add new revenue to the existing revenue with the given ID. showRevenue(id: int) -> int: Return the total revenue for the given ID. Functions should support dynamic input and multiple calls. Assume the system starts with no revenue records. The system should be time-efficient. Example: add(10) -> 1 add(20) -> 2 add(30, 1) -> null showRevenue(1) -> 40 showRevenue(2) -> 20 Constraints: Each call to add and showRevenue should be as quick as possible. revenue is an integer in the range [-10^9, 10^9]. ID is unique and globally incrementing. Example Input add 10 add 20 add 30 1 showRevenue 1 showRevenue 2