public interface Lookup extends Service {
    /**
     * Performs a lookup for given typed component.
     *
     * @param type The component type.
     * @return The component.
     * @param <T> The component type.
     * @throws LookupException if no such component or there is some provisioning related issue.
     */
    @Nonnull
    <T> T lookup(Class<T> type);

    /**

	}
	u := *cache.u // copy
	return &u, nil
}

// cache of the current user
var cache struct {
	sync.Once
	u   *User
	err error
}

// Lookup looks up a user by username. If the user cannot be found, the
// returned error is of type [UnknownUserError].
func Lookup(username string) (*User, error) {
	if u, err := Current(); err == nil && u.Username == username {
		return u, err
	}
	return lookupUser(username)
}

apiVersion: release-notes/v2
kind: bug-fix
area: installation
releaseNotes:
  - |

// will attempt to resolve imports in the $GOPATH workspace.
func ForCompiler(fset *token.FileSet, compiler string, lookup Lookup) types.Importer {
	switch compiler {
	case "gc":
		return &gcimports{
			fset:     fset,
			packages: make(map[string]*types.Package),
			lookup:   lookup,
		}

	case "gccgo":
		var inst gccgoimporter.GccgoInstallation

	)

	data := []*types.Sym{
		abc.Lookup("b"),
		local.Lookup("B"),
		local.Lookup("C"),
		uvw.Lookup("c"),
		local.Lookup("C"),
		gr.Lookup("φ"),
		local.Lookup("Φ"),
		xyz.Lookup("b"),
		abc.Lookup("a"),
		local.Lookup("B"),
	}
	want := []*types.Sym{
		local.Lookup("B"),
		local.Lookup("B"),
		local.Lookup("C"),
		local.Lookup("C"),
		local.Lookup("Φ"),
		abc.Lookup("a"),
		abc.Lookup("b"),

	}

	seven, err := p.Lookup("Seven")
	if err != nil {
		log.Fatalf(`Lookup("Seven") failed: %v`, err)
	}
	if got, want := *seven.(*int), 7; got != want {
		log.Fatalf("plugin1.Seven=%d, want %d", got, want)
	}

	readFunc, err := p.Lookup("ReadCommonX")
	if err != nil {
		log.Fatalf(`plugin1.Lookup("ReadCommonX") failed: %v`, err)
	}

  EXPECT_EQ(value, 4);
  // Insertion of "e" causes "a" to be evicted, but the other entries are still
  // there.
  cache2.Insert("e", 5);
  EXPECT_FALSE(cache2.Lookup("a", &value));
  EXPECT_TRUE(cache2.Lookup("b", &value));
  EXPECT_EQ(value, 2);
  EXPECT_TRUE(cache2.Lookup("c", &value));
  EXPECT_EQ(value, 3);
  EXPECT_TRUE(cache2.Lookup("d", &value));
  EXPECT_EQ(value, 4);

			errStr:   "lookup failed for IP address: lookup 127.0.0.1.1: no such host",
			lookup:   nil,
		},
		{
			name:     "Bad IPv6",
			input:    "[2001:db8::bad::1]:9080",
			expected: "",
			errStr:   "lookup failed for IP address: lookup 2001:db8::bad::1: no such host",
			lookup:   nil,
		},
		{
			name:     "Empty host",
			input:    "",
			expected: "",
			errStr:   ErrResolveNoAddress.Error(),
			lookup:   nil,

    private final Lookup lookup;
    private final RuntimeInformation runtimeInformation;

    @Inject
    @SuppressWarnings("checkstyle:ParameterNumber")
    public DefaultSessionFactory(
            RepositorySystem repositorySystem,
            MavenRepositorySystem mavenRepositorySystem,
            Lookup lookup,
            RuntimeInformation runtimeInformation) {

	}

	af, err := a.Lookup("F")
	if err != nil {
		log.Fatalf(`a.Lookup("F") failed: %v`, err)
	}
	bf, err := b.Lookup("F")
	if err != nil {
		log.Fatalf(`b.Lookup("F") failed: %v`, err)
	}
	if af.(func() interface{})() != bf.(func() interface{})() {
		panic("empty interfaces not equal")
	}

	ag, err := a.Lookup("G")
	if err != nil {
		log.Fatalf(`a.Lookup("G") failed: %v`, err)
	}