'Tries to locate the instance path if it was not provided to the
constructor of the application class.  It will basically calculate
the path to a folder named ``instance`` next to your main file or
the package.
.. versionadded:: 0.8'

def auto_find_instance_path(self):

    (prefix, package_path) = find_package(self.import_name)
    if (prefix is None):
        return os.path.join(package_path, 'instance')
    return os.path.join(prefix, 'var', (self.name + '-instance'))
