docs: def validate_resource(resource) -> None:
      """Validates a resource"""
      if resource is not None and not isinstance(resource, dict):
          raise ValidationError('The resource is not valid.')
  
      if isinstance(resource, dict) and set(resource.keys()) <= {'requests', 'limits'}:
          raise ValidationError(
              'The keys `{}` for the resource are not valid.'.format(set(resource.keys())))