code: def _check_osgb(self, osgb):
      precision = 1
  
      if os.environ.get("PROJ_NETWORK") != "ON":
          grid_name = "uk_os_OSTN15_NTv2_OSGBtoETRS.tif"
          available = (
              Path(pyproj.datadir.get_data_dir(), grid_name).exists()
              or Path(
                  pyproj.datadir.get_user_data_dir(), grid_name
              ).exists()
          )
          if not available:
              import warnings
  
              warnings.warn(
                  f"{grid_name} is unavailable; "
                  "testing OSGB at reduced precision"
              )
              precision = -1
  
      ll = ccrs.Geodetic()
  
      # results obtained by streetmap.co.uk.
      lat, lon = np.array([50.462023, -3.478831], dtype=np.double)
      east, north = np.array([295132.1, 63512.6], dtype=np.double)
  
      # note the handling of precision here...
      assert_almost_equal(
          osgb.transform_point(lon, lat, ll),
          [east, north],
          decimal=precision,
      )
      assert_almost_equal(
          ll.transform_point(east, north, osgb), [lon, lat], decimal=2
      )
  
      r_lon, r_lat = ll.transform_point(east, north, osgb)
      r_inverted = np.array(osgb.transform_point(r_lon, r_lat, ll))
      assert_arr_almost_eq(r_inverted, [east, north], 3)
  
      r_east, r_north = osgb.transform_point(lon, lat, ll)
      r_inverted = np.array(ll.transform_point(r_east, r_north, osgb))
      assert_arr_almost_eq(r_inverted, [lon, lat])
  
imports: import copy
  from io import BytesIO
  import os
  from pathlib import Path
  import pickle
  import warnings
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal
  from numpy.testing import assert_array_almost_equal
  import pyproj
  import pytest
  import shapely.geometry
  import cartopy.crs
label_desc: Use image node_id 3 for calling the TestCRS obj's underlying member method code with example usage: obj._check_osgb(osgb) without return types