Onctuous is a fluid and pleasing to use validation tool you will love to use. Originally based on Voluptuous code by Alec Thomas <firstname.lastname@example.org>, we first fixed long outstanding issues like Python builtins collision and added support for default values.
You can use Onctuous to validate list, scalar (regular variables) or dict. For this purpose, you will need to define a so-called Schema and call the Schema with the input to validate. In case of success, it will return the validated input, possibly filtered or edited according to your rules