def METHOD_NAME(rows, summary=None, open_block=False):
    """Create a section (a details block) for HTML.
    Parameters
    ----------
    rows : sequence of (string, value)
        The data to display, identified by a label and then the value
        to display.
    summary : str or None, optional
        If not None, the summary for the details block
    open_block : bool, optional
        If True then the details block is opened (it is closed by
        default).
    Notes
    -----
    There is no attempt to catch values that could lead to surprising
    output (e.g. injection of HTML).
    """
    out = '<details'
    if open_block:
        out += ' open'
    out += '>'
    if summary is not None:
        out += '<summary>{} ({})</summary>'.format(summary,
                                                   len(rows))
    out += '<div class="datavals">'
    for l, r in rows:
        out += '<div class="dataname">{}</div>'.format(l)
        if isinstance(r, np.ndarray):
            r = show_array(r)
        out += '<div class="dataval">{}</div>'.format(r)
    out += '</div></details>'
    return out