function add_field_to(container_id) {
	var container = document.getElementById(container_id);
	var fieldsets = container.getElementsByTagName("div");
	var number_of_fieldsets = fieldsets.length;
	
	var last_fieldset = fieldsets[fieldsets.length - 1];
	var new_fieldset = last_fieldset.cloneNode(true);
	update_input_labels_in_fieldset(new_fieldset);
	container.appendChild(new_fieldset);
}
;
function update_input_labels_in_fieldset(fieldset) {
	var inputs = fieldset.getElementsByTagName("input")
	for (input_index in inputs) {
		if (input_index != "length"){
			var input = inputs[input_index];
			var name = input.name;
			input.name = update_input_label(name);
			input.value = "";
		}
	}
}
;
function update_input_label(label) {
	counter = label.match(/\d+$/);
	next_value = parseInt(counter) + 1;
	return label.replace(/\d+$/, next_value);
}