class_docstr: Tests correctness of Sigmoid with `low` and `high` parameters set.
class_docstr_tok: ["Tests","correctness","of","Sigmoid","with","`","low","`","and","`","high","`","parameters","set","."]
code: def testLeftTail(self, dtype, do_compile):
      x = np.linspace(-50.0, -8.0, 1000).astype(dtype)
  
      @tf.function(autograph=False, jit_compile=do_compile)
      def fn(x):
          return tf.math.log(sigmoid.Sigmoid().forward(x))
  
      vals = fn(x)
      true_vals = -np.log1p(np.exp(-x))
      self.assertAllClose(true_vals, self.evaluate(vals), atol=1e-3)
  
imports: from absl.testing import parameterized
  import numpy
  from scipy import special
  import tensorflow.compat.v2
  from tensorflow_probability.python.bijectors import bijector_test_util
  from tensorflow_probability.python.bijectors import chain
  from tensorflow_probability.python.bijectors import scale
  from tensorflow_probability.python.bijectors import shift
  from tensorflow_probability.python.bijectors import sigmoid
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 7 for calling the ShiftedScaledSigmoidBijectorTest obj's underlying member method code with example usage: obj.testLeftTail(dtype, do_compile) and returns: tf