CODING A MAP ADT USING LINKED LIST IN PYTHON. Rebuild the given Map ADTs structure with the Linked list method using the python language.

CODING A MAP ADT USING LINKED LIST IN PYTHON. Rebuild the given Map ADTs structure with the Linked list method using the python language. It should include the remove, add, contains, len, show and iter methods.
class Map:
def __init__(self):
self._entryList = list()#empty list initialization

def __len__(self):
return len(self._entryList)

def __contains__(self, key):
ndx = self._findPosition(key)
return ndx is not None

#adds a new entry, or replace value if exists
def add(self, key, value):
ndx = self._findPosition(key)
if ndx is not None: #key found
self._entryList[ndx].value = value
return False
else:
entry = _MapEntry(key,value)
self._entryList.append(entry)
return True

def valueOf(self, key):#what value this key holds
ndx = self._findPosition(key)
assert ndx is not None, "Invalid map key"
return self._entryList[ndx].value

def remove(self, key):
ndx = self._findPosition(key)
assert ndx is not None, "Invalid map key"
self._entryList.pop(ndx)

def __iter__(self):
return _MapIterator(self._entryList)

#helper method - so private
def _findPosition(self, key):
for i in range(len(self)):
if self._entryList[i].key == key:
return i
else:
return None #check if key in ith element, returns None otherwise

class _MapEntry:
def __init__(self, key, value):
self.key = key
self.value = value

class _MapIterator:
def __init__(self, entryList):
self._entryList = entryList
self._index = 0

def __iter__(self):
return self

def __next__(self):
if self._index < len(self._entryList):
element = self._entryList[self._index]
self._index += 1
return element
else:
raise StopIteration