template instance template 'appender' is not defined

[Ali Çehreli via Digitalmars-d-learn]

On 05/31/2015 02:33 PM, Assembly wrote:

>> appender is in std.array.
>>
>> Ali
>
> why that page I've linked use std.format?

Some examples simply use appender. For example, the following appears in 
some of the examples there:

   import std.array : appender;

Ali