Data Validator is a class to validate a set of values based on a list of rules. It supports the following validation orders: sequence (fields validated sequentially), all-at-once, and both (using a dependencies model). It can embed different user-defined validation rules libraries (a default built-in library is provided).
validator.py is a tool for ensuring that data conforms to certain sets of rules, called validations. A validation is essentially a schema for a dictionary, containing a list of rules for each key/value pair in the dictionary you want to validate. This is intended to fill a similar use case to form validations in WTForms or Rails, but for general sources of data, not just Web forms.