* are valid.
   *
   * @param rowKey row key of mapping to be erased
   * @param columnKey column key of mapping to be erased
   * @return the value previously associated with the keys, or {@code null} if no mapping existed
   *     for the keys
   */
  @CanIgnoreReturnValue
  @CheckForNull
  public V erase(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {

    assertEquals((Character) 'b', table.erase("bar", 1));
    assertNull(table.get("bar", 1));
    assertEquals(9, table.size());
    assertNull(table.erase("bar", 1));
    assertNull(table.erase("foo", 2));
    assertNull(table.erase("dog", 1));
    assertNull(table.erase("bar", 5));
    assertNull(table.erase(null, 1));
    assertNull(table.erase("bar", null));
  }

    assertEquals((Character) 'b', table.erase("bar", 1));
    assertNull(table.get("bar", 1));
    assertEquals(9, table.size());
    assertNull(table.erase("bar", 1));
    assertNull(table.erase("foo", 2));
    assertNull(table.erase("dog", 1));
    assertNull(table.erase("bar", 5));
    assertNull(table.erase(null, 1));
    assertNull(table.erase("bar", null));
  }

   * are valid.
   *
   * @param rowKey row key of mapping to be erased
   * @param columnKey column key of mapping to be erased
   * @return the value previously associated with the keys, or {@code null} if no mapping existed
   *     for the keys
   */
  @CanIgnoreReturnValue
  @CheckForNull
  public V erase(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {

  /**
   * Alternate name for {@link #SP}.
   *
   * @since 8.0
   */
  public static final byte SPACE = 32;

  /**
   * Delete: This character is used primarily to "erase" or "obliterate" erroneous or unwanted
   * characters in perforated tape.
   *
   * @since 8.0
   */
  public static final byte DEL = 127;

  /**
   * The minimum value of an ASCII character.
   *

  /**
   * Alternate name for {@link #SP}.
   *
   * @since 8.0
   */
  public static final byte SPACE = 32;

  /**
   * Delete: This character is used primarily to "erase" or "obliterate" erroneous or unwanted
   * characters in perforated tape.
   *
   * @since 8.0
   */
  public static final byte DEL = 127;

  /**
   * The minimum value of an ASCII character.
   *

  /**
   * Creates a new container containing the given elements. TODO: would be nice to figure out how to
   * use E... or E[] as a parameter type, but this doesn't seem to work because Java creates an
   * array of the erased type.
   */
  T create(Object... elements);

  /**
   * Helper method to create an array of the appropriate type used by this generator. The returned
   * array will contain only nulls.
   */

  /**
   * Creates a new container containing the given elements. TODO: would be nice to figure out how to
   * use E... or E[] as a parameter type, but this doesn't seem to work because Java creates an
   * array of the erased type.
   */
  T create(Object... elements);

  /**
   * Helper method to create an array of the appropriate type used by this generator. The returned
   * array will contain only nulls.
   */