Consider the home heating system described below. The software controller of a home heating system regulates the temperature in a home by turning the oil-based furnace on and off, provided the master switch is set to the HEAT position. The furnace heats the water, which then circulates through the house. The controller activates the furnace whenever the home temperature (T) falls below DT2, where DT is the desired temperature set by the user. The details of the furnace activation procedure are described in the following use case: 1. Home owner sets Master Switch to HEAT. 2. System detects that the home temperature is below DT-2. 3. System outputs a start command to the motor. 4. System monitors the motor speed and once the speed has reached the normal operating speed, It outputs an ignite command to the ignition actuator and an open command to the oil valve. 5. System monitors the water temperature and once the temperature has reached a predefined value, it outputs an open command to the circulation valve. 6. Once the home temperature reaches DT+2 degrees, the system deactivates the furnace by first outputting a close command to the oil valve and, after 5 seconds, outputting a stop command to the fan motor and a close command to the circulation valve. Develop a system context diagram showing how the system interfaces to the external environment