@staticmethod
def __check_utm_zone(utm_zone):
    """
        Checks whether UTM grid zone is valid or not.

        Parameters
        ----------
        utm_zone : str
            A string representing an UTM grid zone, containing digits (1 to 60) 
            indicating the longitudinal zone followed by a character (from 'C' 
            to 'X' excluding 'O') corresponding to the latitudinal zone.
        
        Returns
        -------
        out : bool
            A boolean indicating True or False.        
        """
    flag = False
    lat_zones = ['C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P',
        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X']
    try:
        lat_zone = utm_zone[-1].upper()
        long_zone = int(utm_zone[:-1])
        if lat_zone in lat_zones:
            print('Correct latitudinal zone!')
            flag = True
        else:
            print(
                """Incorrect latitudinal zone!                       
Enter a correct latitudinal zone!"""
                )
            flag = False
        if long_zone >= 1 and long_zone <= 60:
            print('Correct longitudinal zone!')
            flag = True and flag
        else:
            print(
                """Incorrect longitudinal zone!                      
Enter a correct longitudinal zone!"""
                )
            flag = False
    except:
        flag = False
        print('Wrong input!\nHint: there should not be spaces' +
            'between longitudinal and latitudinal zones' +
            'when expressing the UTM zone!')
    return flag
