Implement a Linked Positional List.

The linked positional list supports the following functionality:

• Insert First - Insert's an element at the start of the list.

• Insert Last - Insert's an element at the end of the list.

• Insert Before - Inserts an element at the given position.

• Remove - Remove the given element.

• Undo - Undo the action.

Python

The documented positional list interface is in core.py and the class you need to implement is in linked_positional_list.py

insert first A header traler insert_before A B remove A header traler 8 undo header 8 trailer undo header trailer undo header K trale aLANGUAGE linked_positional-list 1 core.py def _init__(self): 35 36 37 38 39 40 41 42 43 # The header sentinel self.-header = Node (None) # The trailer sentinel self._trailerNode (None) # Setting the correct previousext self._header.next -self._trailer self-trailer . prev = self.-header 45 46 47 48 49 50 51 52 53 54 def print list(self) Prints the current state of the list; Starting at the header and moving forwards. current = self.headernext list str" while True: - if currentself.trailer: break liststr"".format(current.get_element()) currentcurrent.next 56 57 58 59 60 61 62 63 64 65 return list str def insert first(self, element) # TODO Implement # Create the new element as the first in the list. return None def insert_last(self, element): # TODO Implement LANGUAGE linked-positional-list.! core.py 1 import abc 2 3 4 class Position (metaclass-abc.ABCMeta): 5 6 7 8 @abc.abstractmethod def get_element (self) """Returns the stored element at this position.""" pass 10 12 class PositionalList (metaclass-abc.ABCMeta) 13 14 15 16 17 18 19 20 21 @abc.abstractmethod def print list(self): Runs a pretty print to print the list out. pass @abc.abstractmethod def insert first(self, element) 23 24 25 26 27 28 29 30 31