def false_negatives(links_true, links_pred):
    """Count the number of False Negatives.

    Returns the number of incorrect predictions of true links. (true links,
    but predicted as non-links). This value is known as the number of False
    Negatives (FN).

    Parameters
    ----------
    links_true: pandas.MultiIndex, pandas.DataFrame, pandas.Series
        The true (or actual) links.
    links_pred: pandas.MultiIndex, pandas.DataFrame, pandas.Series
        The predicted links.

    Returns
    -------
    int
        The number of false negatives.

    """

    links_true = _get_multiindex(links_true)
    links_pred = _get_multiindex(links_pred)

    return len(links_true.difference(links_pred))
Count the number of False Negatives.

    Returns the number of incorrect predictions of true links. (true links,
    but predicted as non-links). This value is known as the number of False
    Negatives (FN).

    Parameters
    ----------
    links_true: pandas.MultiIndex, pandas.DataFrame, pandas.Series
        The true (or actual) links.
    links_pred: pandas.MultiIndex, pandas.DataFrame, pandas.Series
        The predicted links.

    Returns
    -------
    int
        The number of false negatives.