code: def implicit_fcn(self, B, x):
      return (
          B[2] * np.power(x[0] - B[0], 2)
          + 2.0 * B[3] * (x[0] - B[0]) * (x[1] - B[1])
          + B[4] * np.power(x[1] - B[1], 2)
          - 1.0
      )
  
imports: import tempfile
  import shutil
  import os
  import numpy
  from numpy import pi
  from numpy.testing import assert_array_almost_equal, assert_equal, assert_warns
  import pytest
  from pytest import raises
  from scipy.odr import Data, Model, ODR, RealData, OdrStop, OdrWarning, multilinear, exponential, unilinear, quadratic, polynomial
label_desc: Use image node_id 8 for calling the TestODR obj's underlying member method code with example usage: obj.implicit_fcn(B, x) and returns: unknown