code: def _parse_header(cls, header_proto, resource):
          
          header = header_proto()
          try:
              header_bytes = base64.b64decode(resource['header'])
              header.ParseFromString(header_bytes)
          except (KeyError, TypeError, ValueError, DecodeError):
              header = resource.get('header', None)
              LOGGER.error(
                  'The validator sent a resource with %s %s',
                  'a missing header' if header is None else 'an invalid header:',
                  header or '')
              raise errors.ResourceHeaderInvalid()
  
          resource['header'] = cls._message_to_dict(header)
          return resource
docs: Deserializes a resource's base64 encoded Protobuf header.