Implement object which allows write buffering [Simple Snake]

[“Plane” Abhabongse Janthong]

Introduce a callable object which allows writing into the buffer inside the object and introduces a collect method to dump the content from the buffer into the output space every time any evaluation could have happened (i.e. post-visitor hook).

[“Plane” Abhabongse Janthong]

Implemented in 3db9632