Transforms elements emitted by the original flow by applying transform, that returns another flow, and then concatenating and flattening these flows.
This method is a shortcut for
map(transform).flattenConcat(). See flattenConcat.
Note that even though this operator looks very familiar, we discourage its usage in a regular application-specific flows. Most likely, suspending operation in map operator will be sufficient and linear transformations are much easier to reason about.