class_docstr: SEVIRI HRIT prologue reader.
class_docstr_tok: ["SEVIRI","HRIT","prologue","reader","."]
docstr: Read the prologue metadata.
code: def read_prologue(self):
      """Read the prologue metadata."""
      with utils.generic_open(self.filename, mode="rb") as fp_:
          fp_.seek(self.mda["total_header_length"])
          data = np.frombuffer(
              fp_.read(hrit_prologue.itemsize),
              dtype=hrit_prologue,
              count=1,
          )
          self.prologue.update(recarray2dict(data))
          try:
              impf = np.frombuffer(
                  fp_.read(impf_configuration.itemsize),
                  dtype=impf_configuration,
                  count=1,
              )[0]
          except ValueError:
              logger.info(
                  "No IMPF configuration field found in prologue."
              )
          else:
              self.prologue.update(recarray2dict(impf))
  
imports: from __future__ import division
  import copy
  import logging
  from datetime import timedelta
  import dask.array
  import numpy
  import xarray
  from pyresample import geometry
  import satpy.readers.utils
  from satpy._compat import cached_property
  from satpy.readers._geos_area import get_area_definition, get_area_extent, get_geos_area_naming
  from satpy.readers.eum_base import get_service_mode, recarray2dict, time_cds_short
  from satpy.readers.hrit_base import HRITFileHandler, ancillary_text, annotation_header, base_hdr_map, image_data_function
  from satpy.readers.seviri_base import CHANNEL_NAMES, HRV_NUM_COLUMNS, REPEAT_CYCLE_DURATION, SATNUM, NoValidOrbitParams, OrbitPolynomialFinder, SEVIRICalibrationHandler, add_scanline_acq_time, create_coef_dict, get_cds_time, get_satpos, mask_bad_quality, pad_data_horizontally, round_nom_time
  from satpy.readers.seviri_l1b_native_hdr import hrit_epilogue, hrit_prologue, impf_configuration
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 2 for calling the HRITMSGPrologueFileHandler obj's underlying member method code with example usage: obj.read_prologue() without return types