How to use the metview.Fieldset function in metview

import logging
import os
from functools import reduce
from pathlib import Path
from typing import Union

import metview
import numpy as np

logger = logging.getLogger(__name__)


class Fieldset(metview.Fieldset):
    def __init__(self, path):
        raise PermissionError("Initilizing this class directly is not allowed.")

    @property
    def units(self):
        return metview.grib_get_string(self, "units")

    @classmethod
    def from_path(cls, path: Union[Path, str]):
        if isinstance(path, Path):
            path = str(path)

        if not os.path.exists(path):
            raise IOError(f"File does not exist: {path}")

        obj = metview.read(path)