'Get a permission from the database.
Args:
key (str, optional): The permission\'s identifier.
category (str, optional): The permission\'s category.
obj (object, optional): The object on which this Tag is set.
Returns:
permission (list): Permission objects.'

def get_permission(self, key=None, category=None, obj=None):

    return self.get_tag(key=key, category=category, obj=obj, tagtype='permission')
