code: def _get_rows_per_scan(sensor: str) -> Optional[int]:
      """Get number of rows per scan."""
      for k, v in ROWS_PER_SCAN.items():
          if sensor.startswith(k):
              return v
      return None
  
imports: import logging
  import os
  from glob import glob
  from typing import Optional, Union
  import netCDF4
  import numpy
  import xarray
  from pyresample import geometry
  from satpy.readers.file_handlers import BaseFileHandler
  from satpy.readers.hdf4_utils import SDS, HDF4FileHandler
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 3 for calling a global function with example usage: _get_rows_per_scan(sensor) and returns: None, v