No need to use apply as it’s much more useful if you have function name stored in variable.
` response = @some_module_from_config.parse(data)`
Not only it would not give you any benefit, but it would also be wrongly used.
In Handler module you have to define callbacks and / or macrocallbacks. You use @behaviour attribute in CustomerA and CustomerB modules. In this tiny example it’s not important at all, but in general you use this to make sure that all callbacks are implemented as Elixir gives compilation warning otherwise.
