code: def test_scale_factor(self):
      # See #455
      # Use spherical Earth in North Polar Stereographic to check
      # equivalence between true_scale and scale_factor.
      # In these conditions a scale factor of 0.75 corresponds exactly to
      # a standard parallel of 30N.
      globe = ccrs.Globe(ellipse="sphere")
      stereo = ccrs.Stereographic(
          central_latitude=90.0, scale_factor=0.75, globe=globe
      )
      other_args = {
          "ellps=sphere",
          "lat_0=90.0",
          "lon_0=0.0",
          "k_0=0.75",
          "x_0=0.0",
          "y_0=0.0",
      }
      check_proj_params("stere", stereo, other_args)
  
      # Now test projections
      lon, lat = 10, 10
      projected_scale_factor = stereo.transform_point(
          lon, lat, ccrs.Geodetic()
      )
  
      # should be equivalent to North Polar Stereo with
      # true_scale_latitude = 30
      nstereo = ccrs.NorthPolarStereo(
          globe=globe, true_scale_latitude=30
      )
      projected_true_scale = nstereo.transform_point(
          lon, lat, ccrs.Geodetic()
      )
  
      assert projected_true_scale == projected_scale_factor
  
file_path: cartopy/lib/cartopy/tests/crs/test_stereographic.py
imports: import numpy
  from numpy.testing import assert_almost_equal
  import cartopy.crs
  from .helpers import check_proj_params
label_desc: Use image node_id 4 for calling the TestStereographic obj's underlying member method code with example usage: obj.test_scale_factor() without return types