replaced concatenation to f-strings to improve readability and unify … (#29785)

replaced concatenation to f-strings to improve readability and unify with the rest code

src/transformers/tokenization_utils_base.py

@@ -3657,7 +3657,7 @@ class PreTrainedTokenizerBase(SpecialTokensMixin, PushToHubMixin):
                 ids = ids[ids_to_move:]
                 pair_ids = pair_ids[pair_ids_to_move:] if pair_ids is not None else None
             else:
-                raise ValueError("invalid truncation strategy:" + str(self.truncation_side))
+                raise ValueError(f"invalid truncation strategy:{self.truncation_side}")
 
         elif truncation_strategy == TruncationStrategy.ONLY_SECOND and pair_ids is not None:
             if len(pair_ids) > num_tokens_to_remove:
@@ -3669,7 +3669,7 @@ class PreTrainedTokenizerBase(SpecialTokensMixin, PushToHubMixin):
                     overflowing_tokens = pair_ids[:window_len]
                     pair_ids = pair_ids[num_tokens_to_remove:]
                 else:
-                    raise ValueError("invalid truncation strategy:" + str(self.truncation_side))
+                    raise ValueError(f"invalid truncation strategy:{self.truncation_side}")
             else:
                 logger.error(
                     f"We need to remove {num_tokens_to_remove} to truncate the input "
@@ -3753,7 +3753,7 @@ class PreTrainedTokenizerBase(SpecialTokensMixin, PushToHubMixin):
                     encoded_inputs["special_tokens_mask"] = [1] * difference + encoded_inputs["special_tokens_mask"]
                 encoded_inputs[self.model_input_names[0]] = [self.pad_token_id] * difference + required_input
             else:
-                raise ValueError("Invalid padding strategy:" + str(self.padding_side))
+                raise ValueError(f"Invalid padding strategy:{self.padding_side}")
 
         return encoded_inputs