def active_page_number(browser):
    """Returns page number currently active.

    Parameters
    ----------
    browser

    Returns
    -------
    int
    """
    pagination = browser.find_by_id('pagination')
    active_page_items = pagination.find_by_css('li.page-item.active')
    assert len(active_page_items) == 1
    active_page_item = active_page_items.first
    return int(active_page_item.find_by_css('a.page-link').first.text)