Lists are mutable sequences. There are immutable sequences as well.
These are called tuples. Here we create a tuple with A3 and -0.2 in
it, and we assign it to variable tup. Tuples and lists use the same index
notation. Here, we look at tuple at index zero,
index one, index two, and also, we can use negative indices such as tup at index
-one. Slicing a tuple, produces a tuple.
Here, we slice tup up two, but not including index two and we can also slice
tup from index one up to, but not including index three.