code: def _numpyKernel(self, concentration, rate, x, y):
      return np.power(
          rate / (x[..., 0] + y[..., 0] + rate), concentration
      )
  
file_path: probability/tensorflow_probability/python/math/psd_kernels/exponential_curve_test.py
imports: from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.math import gradient
  from tensorflow_probability.python.math.psd_kernels import exponential_curve
label_desc: Use image node_id 1 for calling the ExponentialCurveTest obj's underlying member method code with example usage: obj._numpyKernel(concentration, rate, x, y) and returns: np