Kernel.then

You're seeing just the macro then, go back to Kernel module for more information.
Link to this macro

then(value, fun)

View Source (macro) (since 1.12.0)

Pipes value into the given fun.

In other words, it invokes fun with value as argument. This is most commonly used in pipelines, allowing you to pipe a value to a function outside of its first argument.

Examples

iex> 1 |> then(fn x -> x * 2 end)
2