Error fix

# --- FIX FOR gemma/gm/text/_tokenizer.py ---

class Gemma4Tokenizer(Tokenizer):
"""Tokenizer for Gemma 4 models."""

# ADDITION: Masking multimodal and internal reasoning tokens
FORBIDDEN_TOKENS = (
special_tokens.IMAGE_PLACEHOLDER,
special_tokens.START_OF_IMAGE,
special_tokens.END_OF_IMAGE,
special_tokens.AUDIO_PLACEHOLDER,
special_tokens.START_OF_AUDIO,
special_tokens.END_OF_AUDIO,
special_tokens.THINKING_START,
special_tokens.THINKING_END,
)

def __init__(self, ...):
# existing init logic