OPA syntax question

I have seen in the stdlib and in some github project. 开发者_如何学JAVACode like that :

MyClass =

  field_id(id) = "{id}_field"

{{

my_func(args) = output

}}

What the interest to have function before the {{ }} block ??

It declares the function as private to the module. Equivalent to:

MyClass = {{

  @private
  field_id(id) = "{id}_field"

  my_func(args) = output

}}