Set<String> enemies = newHashSet("Dick", "Harry", "Tom");

    Set<String> goodFriends = Sets.difference(friends, enemies);
    assertEquals(2, goodFriends.size());

    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());

func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {
	nset := NewTargetIDSet()
	for k := range set {
		if _, ok := sset[k]; !ok {
			nset.add(k)
		}
	}

	return nset
}

    Set<String> enemies = newHashSet("Dick", "Harry", "Tom");

    Set<String> goodFriends = Sets.difference(friends, enemies);
    assertEquals(2, goodFriends.size());

    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());

						</difference>
						<difference>
							<className>jcifs/Configuration</className>
							<differenceType>7012</differenceType>
							<method>java.lang.String getGuestPassword()</method>
						</difference>
						<difference>
							<className>jcifs/SmbResource</className>
							<differenceType>7012</differenceType>
							<method>void setFileTimes(long, long, long)</method>
						</difference>
					</ignored>

/**
 * An object representing the differences between two maps.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use Maps.difference")
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
  /**
   * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
   * equal.
   */

		nrules[pattern] = nrules[pattern].Union(targetIDSet)
	}

	return nrules
}

// Difference - returns difference with given rules as new rules.
func (rules Rules) Difference(rules2 Rules) Rules {
	nrules := make(Rules)

	for pattern, targetIDSet := range rules {
		if nv := targetIDSet.Difference(rules2[pattern]); len(nv) > 0 {
			nrules[pattern] = nv
		}
	}

	return nrules

/**
 * An object representing the differences between two maps.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use Maps.difference")
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
  /**
   * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
   * equal.
   */

func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {
	nset := NewTargetIDSet()
	for k := range set {
		if _, ok := sset[k]; !ok {
			nset.add(k)
		}
	}

	return nset
}

## Current Behavior
<!--- If describing a bug, tell us what happens instead of the expected behavior -->
<!--- If suggesting a change/improvement, explain the difference from current behavior -->

## Possible Solution
<!--- Not obligatory, but suggest a fix/reason for the bug, -->
<!--- or ideas how to implement the addition or change -->

## Steps to Reproduce (for bugs)

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Predicates.not;
import static com.google.common.collect.Multisets.difference;
import static com.google.common.collect.Multisets.intersection;
import static com.google.common.collect.Multisets.sum;
import static com.google.common.collect.Multisets.union;