Lamina.config_change

You're seeing just the callback config_change, go back to Lamina module for more information.
Link to this callback

config_change(config_key, old_value, new_value)

Specs

config_change(config_key, old_value, new_value) :: :ok
when config_key: atom(), old_value: any(), new_value: any()

Called when the Lamina.Server detects a configuration change.

This is a simple mechanism to allow the server to notify your system that a configuration value has changed.

See also subscribe/1.