ImmutableList.Builder<V> valuesBuilder = new ImmutableList.Builder<>(map.size());
    for (Entry<Range<K>, ? extends V> entry : map.entrySet()) {
      rangesBuilder.add(entry.getKey());
      valuesBuilder.add(entry.getValue());
    }
    return new ImmutableRangeMap<>(rangesBuilder.build(), valuesBuilder.build());
  }

  /** Returns a new builder for an immutable range map. */

      checkEntryNotNull(key, value);
      ImmutableCollection.Builder<V> valuesBuilder = ensureBuilderMapNonNull().get(key);
      if (valuesBuilder == null) {
        valuesBuilder = newValueCollectionBuilderWithExpectedSize(expectedValuesPerKey);
        ensureBuilderMapNonNull().put(key, valuesBuilder);
      }
      valuesBuilder.add(value);
      return this;
    }

    /**