You may have read the docs on Heroku Logplex drains, but they're a lie. When you create a logplex drain it posts erlang-formatted strings to your app. This means there's a header of metadata, a dash, and then your logline.
This package provides a Transform stream that turns the metadata into logfmt-style data. If your logline is in logfmt format you can parse one uniform string of data instead of having to split the string every time.