bit.ly/tf-sig-build-notes) if you'd like to discuss the future of contributions.

### Brief System Overview

The top-level scripts and utility scripts should be fairly well-documented. Here
is a brief explanation of how they tie together:

1.  `envs/*` are lists of variables made with bash syntax. A user must set a
    `TFCI` env param pointing to a list of `env` files.
2.  `utilities/setup.sh`, initialized by all top-level scripts, reads and sets

   *
   * <ul>
   *   <li>The visible constructor or visible static factory method with the most parameters is used
   *       to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.

   *
   * <ul>
   *   <li>The visible constructor or visible static factory method with the most parameters is used
   *       to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.

   *
   * <ul>
   *   <li>The non-private constructor or non-private static factory method with the most parameters
   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.

 * priority. If you need to enforce an ordering, you can define custom classes or comparators that
 * use a secondary key to break ties in primary priority values. For example, here is a class that
 * applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a
 * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;

 * priority. If you need to enforce an ordering, you can define custom classes or comparators that
 * use a secondary key to break ties in primary priority values. For example, here is a class that
 * applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a
 * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;

   *
   * <ul>
   *   <li>The non-private constructor or non-private static factory method with the most parameters
   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.

  <T2 extends T> Ordering<Entry<T2, ?>> onKeys() {
    return onResultOf(Maps.<T2>keyFunction());
  }

  /**
   * Returns an ordering which first uses the ordering {@code this}, but which in the event of a
   * "tie", then delegates to {@code secondaryComparator}. For example, to sort a bug list first by
   * status and second by priority, you might use {@code byStatus.compound(byPriority)}. For a

    return hextetsToIPv6String(hextets);
  }

  /**
   * Identify and mark the longest run of zeroes in an IPv6 address.
   *
   * <p>Only runs of two or more hextets are considered. In case of a tie, the leftmost run wins. If
   * a qualifying run is found, its hextets are replaced by the sentinel value -1.
   *
   * @param hextets {@code int[]} mutable array of eight 16-bit hextets
   */

  EXPECT_TRUE(absl::StrContains(s, expected))
      << "'" << s << "' does not contain '" << expected << "'";
}

// Returns the GPU device name if there is one (with arbitrary tie breaking if
// there are more than one), or "" otherwise.
string GPUDeviceName(TF_Session* session) {
  std::unique_ptr<TF_Status, decltype(&TF_DeleteStatus)> status(
      TF_NewStatus(), TF_DeleteStatus);