docs: def custom_function(func, input_files, output_file):
      """
      Calls a custom function which must create the output file.
  
      The custom function takes 3 parameters: ``input_files``,
      ``output_file`` and a boolean ``release``.
      """
      from .modules import utils
  
      return {
          'dependencies_fn': utils.no_dependencies,
          'compiler_fn': func,
          'input': input_files,
          'output': output_file,
          'kwargs': {},
      }