How to use the yamale.util.get_keys function in yamale

def _validate_static_map_list(self, validator, data, path, strict):
        if util.is_map(validator) and not util.is_map(data):
            return ["%s : '%s' is not a map" % (path, data)]

        if util.is_list(validator) and not util.is_list(data):
            return ["%s : '%s' is not a list" % (path, data)]

        errors = []

        if strict:
            data_keys = set(util.get_keys(data))
            validator_keys = set(util.get_keys(validator))
            for key in data_keys - validator_keys:
                error_path = path + DataPath(key)
                errors += ['%s: Unexpected element' % error_path]

        for key, sub_validator in util.get_iter(validator):
            errors += self._validate_item(sub_validator,
                                          data,
                                          path,
                                          strict,
                                          key)
        return errors

def _validate_map_list(self, validator, data, path, strict):
        errors = []

        if not validator.validators:
            return errors  # No validators, user just wanted a map.

        for key in util.get_keys(data):
            sub_errors = []
            for v in validator.validators:
                err = self._validate_item(v, data, path, strict, key)
                if err:
                    sub_errors.append(err)

            if len(sub_errors) == len(validator.validators):
                # All validators failed, add to errors
                for err in sub_errors:
                    errors += err

        return errors

def _validate_static_map_list(self, validator, data, path, strict):
        if util.is_map(validator) and not util.is_map(data):
            return ["%s : '%s' is not a map" % (path, data)]

        if util.is_list(validator) and not util.is_list(data):
            return ["%s : '%s' is not a list" % (path, data)]

        errors = []

        if strict:
            data_keys = set(util.get_keys(data))
            validator_keys = set(util.get_keys(validator))
            for key in data_keys - validator_keys:
                error_path = path + DataPath(key)
                errors += ['%s: Unexpected element' % error_path]

        for key, sub_validator in util.get_iter(validator):
            errors += self._validate_item(sub_validator,
                                          data,
                                          path,
                                          strict,
                                          key)
        return errors