'Overrides S3FilterWidget.data_element(), constructs multiple
hidden INPUTs (one per variable) with element IDs of the form
<id>-<operator>-data (where no operator is translated as "eq").
@param variables: the variables'

def data_element(self, variables):

    if (variables is None):
        operators = self.operator
        if (type(operators) is not list):
            operators = [operators]
        variables = self._variable(self.selector, operators)
    else:
        if (type(variables) is not list):
            variables = [variables]
        operators = [(v.split('__')[1] if ('__' in v) else 'eq') for v in variables]
    elements = []
    id = self.attr['_id']
    for (o, v) in zip(operators, variables):
        elements.append(INPUT(_type='hidden', _id=('%s-%s-data' % (id, o)), _class=('filter-widget-data    %s-data' % self._class), _value=v))
    return elements
