Utilities for splitting Pair instances emitted by DoFn into
separate PCollection instances. A typical motivation for this might
be to separate standard output from error output of a DoFn.
split(PCollection<Pair<T,U>> pCollection)
Splits a PCollection of any Pair of objects into a Pair of
PCollection}, to allow for the output of a DoFn to be handled using
separate channels.
split(PCollection<Pair<T,U>> pCollection,
PType<T> firstPType,
PType<U> secondPType)
Splits a PCollection of any Pair of objects into a Pair of
PCollection}, to allow for the output of a DoFn to be handled using
separate channels.