getInputElementsByFormGroup(form_group_el_or_id) {
        if (typeof form_group_el_or_id === 'string') {
            var form_group = document.getElementById(form_group_el_or_id);
        } else {
            var form_group = form_group_el_or_id;
        }
        var input = form_group.querySelector('[name]');
        var label = form_group.getElementsByTagName('label')[0];
        if (label === undefined) {
            label = null;
        }
        return {
            formGroup: form_group,
            input: input,
            label: label
        }
    }
Return form group element, input element and label element
@param form_group_el_or_id
@returns {object} 3 keys: formGroup, input, label