Amqpx.Gen.Producer.publish_by

You're seeing just the function publish_by, go back to Amqpx.Gen.Producer module for more information.
Link to this function

publish_by(producer_name, exchange_name, routing_key, payload, options \\ [])

Specs

publish_by(
  producer_name :: GenServer.name(),
  exchange_name :: String.t(),
  routing_key :: String.t(),
  payload :: String.t(),
  options :: Keyword.t()
) :: :ok | :error