string([]byte{'a'})      // not a constant: []byte{'a'} is not a constant
(*int)(nil)              // not a constant: nil is not a constant, *int is not a boolean, numeric, or string type
int(1.2)                 // illegal: 1.2 cannot be represented as an int
string(65.0)             // illegal: 65.0 is not an integer constant
</pre>

<p>
A non-constant value <code>x</code> can be converted to type <code>T</code>

 * this file is open. This constant may be logically OR'd with other share
 * access flags.
 */
    public static final int FILE_SHARE_READ   = 0x01;
/**
 * When specified as the <tt>shareAccess</tt> constructor parameter,
 * other SMB clients will be permitted to write to the target file while
 * this file is open. This constant may be logically OR'd with other share
 * access flags.
 */

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.base.Functions.constant;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

door as you are; secondly, because they're making such a noise
inside, no one could possibly hear you.'  And certainly there was
a most extraordinary noise going on within--a constant howling
and sneezing, and every now and then a great crash, as if a dish
or kettle had been broken to pieces.

  `Please, then,' said Alice, `how am I to get in?'

    /**
     * Returns true if a new value is currently loading, regardless of whether there is an existing
     * value. It is assumed that the return value of this method is constant for any given
     * ValueReference instance.
     */
    boolean isLoading();

    /**
     * Returns true if this reference contains an active value, meaning one that is still considered