def get_file_name(latitude, longitude)
            north_south = latitude >= 0 ? 'N' : 'S'
            east_west = longitude >= 0 ? 'E' : 'W'

            lat = latitude.floor.to_i.abs.to_s.rjust(2, '0')
            lon = longitude.floor.to_i.abs.to_s.rjust(3, '0')

            "#{north_south}#{lat}#{east_west}#{lon}.hgt"
        end
def get_file_name(latitude, longitude)
            north_south = latitude >= 0 ? 'N' : 'S'
            east_west = longitude >= 0 ? 'E' : 'W'

            lat = latitude.floor.to_i.abs.to_s.rjust(2, '0')
            lon = longitude.floor.to_i.abs.to_s.rjust(3, '0')

            "#{north_south}#{lat}#{east_west}#{lon}.hgt"
        end
Return the file name no matter if the actual SRTM file exists.