@observe('enable_html_pager')
def _enable_html_pager_changed(self, change):
    if change['new']:
        warn('`enable_html_pager` is provisional since IPython 5.0 and might change in future versions.', ProvisionalWarning)
@observe('enable_html_pager')
def _enable_html_pager_changed(self, change):
    if change['new']:
        warn('`enable_html_pager` is provisional since IPython 5.0 and might change in future versions.', ProvisionalWarning)