Check that all the instances have the same types.

def _check_types(self) -> None:
        """
        Check that all the instances have the same types.
        """
        all_instance_fields_and_types: List[Dict[str, str]] = [{k: v.__class__.__name__
                                                                for k, v in x.fields.items()}
                                                               for x in self.instances]
        # Check all the field names and Field types are the same for every instance.
        if not all([all_instance_fields_and_types[0] == x for x in all_instance_fields_and_types]):
            raise ConfigurationError("You cannot construct a Batch with non-homogeneous Instances.")