def _ensure_tf_install():  # pylint: disable=g-statement-before-imports
  """
  """
  try:
    import tensorflow as tf
  except ImportError:
    # Print more informative error message, then reraise.
    print("\n\nFailed to import TensorFlow. Please note that TensorFlow is not "
          "installed by default when you install TensorFlow Probability. This "
          "is so that users can decide whether to install the GPU-enabled "
          "TensorFlow package. To use TensorFlow Probability, please install "
          "the most recent version of TensorFlow, by following instructions at "
          "https://tensorflow.org/install.\n\n")
    raise

  import distutils.version

  #
  # Update this whenever we need to depend on a newer TensorFlow release.
  #
  required_tensorflow_version = "1.13"

  if (distutils.version.LooseVersion(tf.__version__) <
      distutils.version.LooseVersion(required_tensorflow_version)):
    raise ImportError(
        "This version of TensorFlow Probability requires TensorFlow "
        "version >= {required}; Detected an installation of version {present}. "
        "Please upgrade TensorFlow to proceed.".format(
            required=required_tensorflow_version,
            present=tf.__version__))