def check_before_run(self, required_files):
        """Checks if required files exist before going deeper.
        Args:
            required_files (str or list): string file name(s).
        """
        if isinstance(required_files, str):
            required_files = [required_files]

        for fpath in required_files:
            if not os.path.exists(fpath):
                raise RuntimeError('"{}" is not found'.format(fpath))
Checks if required files exist before going deeper.
        Args:
            required_files (str or list): string file name(s).
        
projects/FastAttr/fastattr/datasets/bases.py