lastline firstline curline curlinendx curcolndx numlines insertmode true editbuffer python list editbuffernode figure the doubly linked list of vectors used to implement the edit buffer adt representing the text document from figure partial implementation of the editbuffer class is provided in listing the implementation of some operations and helper methodsmany of which can be implemented in similar fashion to those providedare left as exercises several of the operations simply provide status information and are straightforward in their implementation these are provided in the listing without commentary others are more involved and require brief discussionwhich is provided the following sections listing the editbuffer py module implements the edit buffer adt using doubly linked list of vectors class editbuffer constructs an edit buffer containing one empty line of text def __init__self )self _firstline _editbuffernode['\ 'self _lastline self _firstline self _curline self _firstline self _curlinendx self _curcolndx self _numlines self _insertmode true returns the number of lines in the buffer def numlinesself )return self _numlines (listing continued