import static java.util.Arrays.asList;
import static java.util.Collections.unmodifiableSet;
import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertFalse;
import static junit.framework.Assert.assertTrue;
import static junit.framework.Assert.fail;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Ordering;

    Iterable<String> list = Lists.newArrayList("cool", "pants");
    Iterator<String> iterator = list.iterator();
    assertThat(Iterators.tryFind(iterator, Predicates.alwaysFalse())).isAbsent();
    assertFalse(iterator.hasNext());
  }

  public void testTransform() {
    Iterator<String> input = asList("1", "2", "3").iterator();
    Iterator<Integer> result =
        Iterators.transform(

    checkNotNull(predicate);
    while (iterator.hasNext()) {
      T t = iterator.next();
      if (predicate.apply(t)) {
        return Optional.of(t);
      }
    }
    return Optional.absent();
  }

  /**
   * Returns the index in {@code iterator} of the first element that satisfies the provided {@code
   * predicate}, or {@code -1} if the Iterator has no such elements.
   *