Well, what's the problem. They have bacon and they have ice cr... oh I see the error now. Just add a generic response the ice cream machine is broken and move on!
List comprehensions return a new list. For the sake of code clarity, you probably shouldn't change a second list from within a list comprehension. If you're trying to concatenate two lists, you can do so in a second line:
a = list(range(10))
b = [ value for value in range(5) ]
a.extend(b)
# a has 15 elements
print(a)
surely these are things that should be considered, but they move in relation to what? And is this surprising amount of any significance for tens or hundreds of miles of rail?
you're thinking anywhere on the platform, I'm suggesting a known place near a station by which the train passes and its location - at that moment - is known.
All the system needs is a ground-truth location after a certain amount of time. GPS is just a cheap and convenient way to do it almost anywhere, but this location correction doesn't need to be satellite-based at all.
the initial location doesn't need to be GPS, just a known anchor location. Which is trivial to implement in the case of trains, since stations don't move that drastically.
