def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def _prepare_streams(self) -> None:
        if self._write_stream is not None:
            return
        if self.filename:
            filepath = os.path.join(self.dirpath, self._prepare_filename())
            fs = get_filesystem(filepath)
            file = fs.open(filepath, "a")
            self._output_file = file
            self._write_stream = file.write
        else:
            self._write_stream = self._rank_zero_info