code: def test_fill_value(self):
      x = [(0, 0), (0, 1), (1, 0)]
      y = [1, 2, 3]
  
      yi = griddata(x, y, [(1, 1), (1, 2), (0, 0)], fill_value=-1)
      assert_array_equal(yi, [-1.0, -1, 1])
  
      yi = griddata(x, y, [(1, 1), (1, 2), (0, 0)])
      assert_array_equal(yi, [np.nan, np.nan, 1])
  
imports: import numpy
  from numpy.testing import assert_equal, assert_array_equal, assert_allclose
  import pytest
  from pytest import raises
  from scipy.interpolate import griddata, NearestNDInterpolator, LinearNDInterpolator, CloughTocher2DInterpolator
label_desc: Use image node_id 1 for calling the TestGriddata obj's underlying member method code with example usage: obj.test_fill_value() without return types