Google\Cloud\Datastore\Key::setLastElementIdentifier PHP Method

    public function setLastElementIdentifier($value, $type = Key::TYPE_ID)
    {
        $end = $this->pathEnd();
        $end[$type] = (string) $value;
        $elements = array_keys($this->path);
        $lastElement = end($elements);
        $this->path[$lastElement] = $end;
    }

 public function testSetLastElementIdentifierTypeName()
 {
     $key = new Key('foo', ['path' => [['kind' => 'foo', 'id' => 2], ['kind' => 'foo']]]);
     $key->setLastElementIdentifier(1, Key::TYPE_NAME);
     $this->assertEquals($key->path(), [['kind' => 'foo', 'id' => 2], ['kind' => 'foo', 'name' => 1]]);
 }