<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def validate_regions_schema(self, data):
 """Performs field validation for regions. This should be a dict with region names as the key and RegionSchema as the value """

        region_schema = RegionSchema()
        supplied_regions = data.get('regions', {})
        for region in supplied_regions.keys():
            result = region_schema.validate(supplied_regions[region])
            if len(result.keys()) > 0:
                raise ValidationError(result)