assertThat(FluentIterable.from(list).first()).hasValue("a");
  }

  public void testFirst_null() {
    List<String> list = Lists.newArrayList(null, "a", "b");
    assertThrows(NullPointerException.class, () -> FluentIterable.from(list).first());
  }

  public void testFirst_emptyList() {
    List<String> list = emptyList();
    assertThat(FluentIterable.from(list).first()).isAbsent();
  }

else
  FROM_ENV=$(mktemp)
  # "export -p" prints a list of environment values in a safe-to-source format,
  # e.g. `declare -x TFCI_BAZEL_COMMON_ARGS="list of args"` for bash.
  export -p | grep TFCI > "$FROM_ENV"

  # Source the default ci values
  source ./ci/official/envs/ci_default

  # TODO(angerson) write this documentation
  # Sources every env, in order, from the comma-separated list "TFCI"

  // The number of compression rounds.
  private final int c;
  // The number of finalization rounds.
  private final int d;
  // Two 64-bit keys (represent a single 128-bit key).
  private final long k0;
  private final long k1;

  /**
   * @param c the number of compression rounds (must be positive)
   * @param d the number of finalization rounds (must be positive)

   * <p>The implementation deviates from the {@code ExecutorService} specification with regards to
   * the {@code shutdownNow} method. First, "best-effort" with regards to canceling running tasks is
   * implemented as "no-effort". No interrupts or other attempts are made to stop threads executing
   * tasks. Second, the returned list will always be empty, as any submitted task is considered to

   * the returned list is unspecified.
   *
   * <p>The returned list may have unexpected behavior if it contains {@code NaN}, or if {@code NaN}
   * is used as a parameter to any of its methods.
   *
   * <p>The returned list is serializable.
   *
   * <p><b>Note:</b> when possible, you should represent your data as an {@link

  <offline>false</offline>
  -->

  <!-- pluginGroups
   | This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.
   | when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers
   | "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.
   |-->
  <pluginGroups>
    <!-- pluginGroup

			if hi < lo {
				lo, hi = hi, lo
			}
			// Check there are no duplicates in the register list.
			for i := 0; lo <= hi && i < maxReg; i++ {
				if bits&(1<<lo) != 0 {
					p.errorf("register R%d already in list", lo)
				}
				bits |= 1 << lo
				lo++
			}
		default:
			p.errorf("unexpected register list")
		}
		if p.peek() != ']' {
			p.get(',')
		}
	}
	a.Type = obj.TYPE_REGLIST

	var field []byte
	_ = field
	var zb0001 uint32
	zb0001, err = dc.ReadMapHeader()
	if err != nil {
		err = msgp.WrapError(err)
		return
	}
	var zb0001Mask uint8 /* 3 bits */
	_ = zb0001Mask
	for zb0001 > 0 {
		zb0001--
		field, err = dc.ReadMapKeyPtr()
		if err != nil {
			err = msgp.WrapError(err)
			return
		}
		switch msgp.UnsafeString(field) {
		case "e":

</blockquote>

## Investigation

By using all the previous alternatives I had the chance to learn from all of them, take ideas, and combine them in the best way I could find for myself and the teams of developers I have worked with.

  }

  static final class KeySet<K> extends ImmutableSet<K> {
    private final transient ImmutableMap<K, ?> map;
    private final transient ImmutableList<K> list;

    KeySet(ImmutableMap<K, ?> map, ImmutableList<K> list) {
      this.map = map;
      this.list = list;
    }

    @Override
    public UnmodifiableIterator<K> iterator() {
      return asList().iterator();
    }

    @Override