public long count() {
    return xStats.count();
  }

  /** Returns an immutable snapshot of the statistics on the {@code x} values alone. */
  public Stats xStats() {
    return xStats.snapshot();
  }

  /** Returns an immutable snapshot of the statistics on the {@code y} values alone. */
  public Stats yStats() {
    return yStats.snapshot();
  }

  /**

  public long count() {
    return xStats.count();
  }

  /** Returns the statistics on the {@code x} values alone. */
  public Stats xStats() {
    return xStats;
  }

  /** Returns the statistics on the {@code y} values alone. */
  public Stats yStats() {
    return yStats;
  }

  /**
   * Returns the population covariance of the values. The count must be non-zero.
   *

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Agreement.

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      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a

      use, offer to sell, sell, import, and otherwise transfer the Work,
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      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a

      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a

      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a

      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a

 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMultiset} forward <b>indiscriminately</b> to
 * the methods of the delegate. For example, overriding {@link #add(Object, int)} alone <b>will
 * not</b> change the behavior of {@link #add(Object)}, which can lead to unexpected behavior. In
 * this case, you should override {@code add(Object)} as well, either providing your own