Dart Computer Programming for Intermediates: 07 Transformer
Stream Transformer is a way to simply change the Stream into some other Stream. The built in transformers include: map, where, expand, and take.
map - can change or add to each data value in the Stream
where - continues according to a condition (bool)
expand - adds additional values to the Stream
take - stops the Stream after a given number of data points have passed
transform - allows you to change your streams in manners not stated above. I don't have good examples here.