import static com.google.common.graph.GraphConstants.DEFAULT_NODE_COUNT;
import static com.google.common.graph.Graphs.checkNonNegative;

import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import javax.annotation.CheckForNull;

/**
 * Standard implementation of {@link ValueGraph} that supports the options supplied by {@link
 * AbstractGraphBuilder}.
 *