adds get_values method to our Hash implementation
adds a default/topic field concept, called "_", which when a transform has only one field to work as an input, or as an output, will be used if no other is provided.
adds a Sort transform that (oh god) will sort the input rows using a provided key and a comparison algorithm. This transform is blocking the stream, as it needs EOS signal to be certain it can yield some values, and thus is probably not a good idea to use, unless this point is understood and accepted.