An embedded system is implemented using an RTOS. The system has two push buttons B1 and B2 that are polled and three LEDs to be turned on and off. At all times, one of the LEDs is flashing, with equal on and off times. Pressing B1 cycles through the three LEDs; pressing B2 cycles through a set of times, used to control the flashing rate. The number of times is not yet determined, but will be specified as whole numbers of RTOS ticks. (i) Suggest how many threads you would use to design this application and the role of each thread. (ii) Explain how the threads in you design will interact. You should describe the RTOS API calls used but exact names are not required