code: def test_contrast():
      transfo = T.RandomContrast(delta=0.2)
      input_t = tf.cast(tf.fill([8, 32, 32, 3], 0.5), dtype=tf.float32)
      out = transfo(input_t)
  
      assert tf.reduce_all(out == 0.5)
  
      # FP16
      if any(tf.config.list_physical_devices("GPU")):
          input_t = tf.cast(
              tf.fill([8, 32, 32, 3], 0.5), dtype=tf.float16
          )
          out = transfo(input_t)
          assert out.dtype == tf.float16
  
imports: import math
  import numpy
  import pytest
  import tensorflow
  from doctr import transforms
  from doctr.transforms.functional import crop_detection, rotate_sample
label_desc: Use image node_id 8 for calling a global function with example usage: test_contrast() without return types