def _build_module_seperator(module, submodule=''):
    """
    Creates a string line with a seperator for module and submodule.
    Args:
        - module (String): Name of the module for the seperator
        - submodule (String): Name of the submodule for the seperator (default:
          empty string)
    Returns:
        - (String): Seperator of the form: // Defines for module->submodule
    """
    line = '\n// Defines for {}'.format(module)
    if submodule:
        line += '-> {}'.format(submodule)
    line += '\n'
    return line