def parse_hook_module(hook_module):
    """ Parse a hook_module and split it into two parts

    >>> parse_hook_module('django.core.handlers.base::BaseHandler')
    ['django.core.handlers.base', 'BaseHandler']
    >>> parse_hook_module('django.core.handlers.base')
    ['django.core.handlers.base', None]
    """
    if "::" in hook_module:
        return hook_module.split("::", 1)
    else:
        return [hook_module, None]