You're seeing just the function finch, go back to Req module for more information.

Make the HTTP request using Finch.

This is a request step but it is not documented as such because you don't need to add it to your request pipeline. It is automatically added by run/1 as always the very last request step.

This function shows you that making the actual HTTP call is just another request step, which means that you can write your own step that uses another underlying HTTP client like :httpc, :hackney, etc.