def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def allowed_file(filename):
    return '.' in filename and \
           filename.rsplit('.', 1)[1] in app.config.get('ALLOWED_EXTENSIONS')