def add_from_file(self, f):
        """
        Loads a pre-existing dictionary from a text file and adds its symbols to this instance.
        """
        if isinstance(f, str):
            try:
                with open(f, "r", encoding="utf-8") as fd:
                    self.add_from_file(fd)
            except FileNotFoundError as fnfe:
                raise fnfe
            except UnicodeError:
                raise Exception("Incorrect encoding detected in {}, please rebuild the dataset".format(f))
            return

        lines = f.readlines()
        indices_start_line = self._load_meta(lines)

        for line in lines[indices_start_line:]:
            try:
                line, field = line.rstrip().rsplit(" ", 1)
                if field == "#fairseq:overwrite":
                    overwrite = True
                    line, field = line.rsplit(" ", 1)
                else:
                    overwrite = False
                count = int(field)
                word = line
                if word in self and not overwrite:
                    raise RuntimeError(
                        "Duplicate word found when loading Dictionary: '{}'. "
                        "Duplicate words can overwrite earlier ones by adding the "
                        "#fairseq:overwrite flag at the end of the corresponding row "
                        "in the dictionary file. If using the Camembert model, please "
                        "download an updated copy of the model file.".format(word)
                    )
                self.add_symbol(word, n=count, overwrite=overwrite)
            except ValueError:
                raise ValueError("Incorrect dictionary format, expected '<token> <cnt> [flags]'")

        Loads a pre-existing dictionary from a text file and adds its symbols to this instance.
        
dpkd/transformers/src/transformers/models/biogpt/convert_biogpt_original_pytorch_checkpoint_to_pytorch.py