A common use case for groupBy.
A common use case for groupBy. Takes in a sequence of pairs, groups them by the first element, and returns a map from the group identifier to a sequence of second elements of the matching pairs. E.g., ((a,1), (b,2), (a,3), (b,4)) turns into {a -> (1,3), b -> (2,4)}
Various convenient utilities for Scala constructs.