code: def _forward(self, x):
      x = tf.convert_to_tensor(x)
      # Remove the first row and last column so we can extract strictly
      # lower triangular entries.
      n = x.shape[-1]
      t = tf.linalg.band_part(
          x[..., 1:, :-1], num_lower=n - 1, num_upper=0
      )
      return fill_triangular.FillTriangular().inverse(t)
  
imports: import itertools
  from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.bijectors import bijector
  from tensorflow_probability.python.bijectors import bijector_test_util
  from tensorflow_probability.python.bijectors import correlation_cholesky
  from tensorflow_probability.python.bijectors import fill_triangular
  from tensorflow_probability.python.distributions import beta
  from tensorflow_probability.python.distributions import cholesky_lkj
  from tensorflow_probability.python.distributions import lkj
  from tensorflow_probability.python.distributions.internal import statistical_testing
  from tensorflow_probability.python.internal import tensorshape_util
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.mcmc import hmc
  from tensorflow_probability.python.mcmc import sample
  from tensorflow_probability.python.mcmc import transformed_kernel
label_desc: Use image node_id 2 for calling the OutputToUnconstrained obj's underlying member method code with example usage: obj._forward(x) and returns: fill_triangular