del processed_inputs[c]
                transformed_batch = {**inputs_to_merge, **processed_inputs}
                if transformed_batch:
                    first_col = next(iter(transformed_batch))
                    bad_cols = [
                        col
                        for col in transformed_batch
                        if len(transformed_batch[col]) != len(transformed_batch[first_col])
                    ]
                    if bad_cols:
                        raise ValueError(
                            f"Column lengths mismatch: columns {bad_cols} have length {[len(transformed_batch[col]) for col in bad_cols]} "
                            f"while {first_col} has length {len(transformed_batch[first_col])}."
                        )
                if self.features:
                    for c in self.features.keys():
                        if c not in transformed_batch: