src/transformers/models/openai/tokenization_openai.py/OpenAIGPTTokenizer/convert_tokens_to_string
class OpenAIGPTTokenizer:    def convert_tokens_to_string(self, tokens):
        """Converts a sequence of tokens (string) in a single string."""
        out_string = "".join(tokens).replace("</w>", " ").strip()
        return out_string