return backingMap.isEmpty();
    }

    @Override
    public void clear() {
      backingMap.clear();
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>The set's iterator traverses the mappings for the first row, the mappings for the second
   * row, and so on.
   *
   * <p>Each cell is an immutable snapshot of a row key / column key / value mapping, taken at the

    // benchmarking shows it can take 7 times longer than the other two in some cases. The other two
    // do n swaps, minus a delta (0 or 2 for Reversal, gcd(d, n) for Successive), so that's about
    // twice as many reads and writes. But benchmarking shows that they usually perform better than
    // Dolphin. Reversal is about as good as Successive on average, and it is much simpler,
    // especially since we already have a `reverse` method.

    }

    /**
     * Recursively scan the given directory, adding resources for each file encountered. Symlinks
     * which have already been traversed in the current tree path will be skipped to eliminate
     * cycles; otherwise symlinks are traversed.
     *
     * @param directory the root of the directory to scan
     * @param packagePrefix resource path prefix inside {@code classloader} for any files found

        keyIterator.remove();
      }
      totalSize--;
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>The iterator generated by the returned collection traverses the values for one key, followed
   * by the values of a second key, and so on.
   */
  @Override
  public Collection<V> values() {
    return super.values();
  }

  @Override

     */
    @Nonnull
    List<Profile> getDeclaredProfiles();

    /**
     * Returns all profiles defined in this project and all of its parent projects.
     * <p>
     * This method traverses the parent hierarchy and includes profiles defined in parent POMs.
     * The returned list contains profiles from the current project and all of its ancestors in
     * the project inheritance chain.
     *

  }

  @Override
  Multiset<K> createKeys() {
    return new Multimaps.Keys<K, V>(this);
  }

  /**
   * {@inheritDoc}
   *
   * <p>The iterator generated by the returned collection traverses the values in the order they
   * were added to the multimap. Because the values may have duplicates and follow the insertion
   * ordering, this method returns a {@link List}, instead of the {@link Collection} specified in

func (e *FuncExpr) aggregateRow(r Record, tableAlias string) error {
	switch e.getFunctionName() {
	case aggFnAvg, aggFnSum, aggFnMax, aggFnMin, aggFnCount:
		return e.evalAggregationNode(r, tableAlias)
	default:
		// TODO: traverse arguments and call aggregateRow on
		// them if they could be an ancestor of an
		// aggregation.
	}
	return nil
}

// getAggregate() implementation for each AST node follows. This is

  }

  @Override
  Multiset<K> createKeys() {
    return new Multimaps.Keys<K, V>(this);
  }

  /**
   * {@inheritDoc}
   *
   * <p>The iterator generated by the returned collection traverses the values in the order they
   * were added to the multimap. Because the values may have duplicates and follow the insertion
   * ordering, this method returns a {@link List}, instead of the {@link Collection} specified in

  }

  /**
   * Returns an unmodifiable set of all row key / column key / value triplets. Changes to the table
   * will update the returned set.
   *
   * <p>The returned set's iterator traverses the mappings with the first row key, the mappings with
   * the second row key, and so on.
   *
   * <p>The value in the returned cells may change if the table subsequently changes.
   *

  /**
   * Discouraged synonym for {@link #compareFalseFirst}.
   *
   * @deprecated Use {@link #compareFalseFirst}; or, if the parameters passed are being either
   *     negated or reversed, undo the negation or reversal and use {@link #compareTrueFirst}.
   * @since 19.0
   */
  @InlineMe(replacement = "this.compareFalseFirst(left, right)")
  @Deprecated
  public final ComparisonChain compare(Boolean left, Boolean right) {