A message along a path

You will work out the time that a message needs along two paths made of fibres and chemical synapses. The model values are in the lesson: each chemical synapse adds a delay of 0.5 ms.

The idea. In a fibre, time = length ÷ speed. A message that crosses synapses also pays the delay of each one.

Your tasks.

1. Finish fibre_time. It gives the time in milliseconds for a length in metres and a speed in m/s.
2. Finish total_time. It takes a list of (length, speed) fibres and the number of synapses, and gives the total time in milliseconds.
3. Set faster to "A" or "B", the path with the smaller total time.