class_docstr: File handler for NC seviri files.
  
  **Calibration**
  
  See :mod:`satpy.readers.seviri_base`. Note that there is only one set of
  calibration coefficients available in the netCDF files and therefore there
  is no `calib_mode` argument.
  
  **Metadata**
  
  See :mod:`satpy.readers.seviri_base`.
code: def _get_acq_time_visir(self, dataset_id):
      band_idx = list(CHANNEL_NAMES.values()).index(dataset_id["name"])
      day_key = (
          "channel_data_visir_data_l10_line_mean_acquisition_time_day"
      )
      msec_key = (
          "channel_data_visir_data_l10_line_mean_acquisition_msec"
      )
      days = self.nc[day_key].isel(channels_vis_ir_dim=band_idx)
      msecs = self.nc[msec_key].isel(channels_vis_ir_dim=band_idx)
      return days, msecs
  
imports: import datetime
  import logging
  from datetime import timedelta
  import numpy
  from satpy._compat import cached_property
  from satpy.readers._geos_area import get_area_definition, get_geos_area_naming
  from satpy.readers.eum_base import get_service_mode
  from satpy.readers.file_handlers import BaseFileHandler, open_dataset
  from satpy.readers.seviri_base import CHANNEL_NAMES, SATNUM, NoValidOrbitParams, OrbitPolynomialFinder, SEVIRICalibrationHandler, add_scanline_acq_time, get_cds_time, get_satpos, mask_bad_quality, round_nom_time
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 20 for calling the NCSEVIRIFileHandler obj's underlying member method code with example usage: obj._get_acq_time_visir(dataset_id) and returns: days,  msecs