Python3 Linked List implementation

PyLinkedList.py

class Node:
    def __init__(self, data, nextNode=None):
        self.data = data
        self.next = nextNode

    def __str__ (self):
        return str(self.data)

class PyLinkedList:
    def __init__(self):
        # TODO: create a new node in the constructor
        self._head = None
        self._size = 0

    def size(self):
        return self._size

    def add(self, data):
        node = Node(data, self._head)
        self._head = node
        self._size += 1

    def remove(self, data):
        current = self._head
        prev = None
        while current:
            if current.data == data:
                if current == self._head:
                    self._head = current.next
                else:
                    prev.next = current.next
                self._size -= 1
                return current
            else:
                prev = current
                current = current.next
        return ValueError("{} does not exist in the linked list".format(data))

    def find(self, data):
        current = self._head
        while current:
            if current.data == data:
                return current
            current = current.next
        return ValueError("{} does not exist in the linked list".format(data))

    def __repr__(self):
        return "[{}]".format(", ".join(map(str, self)))

    def __iter__(self):
        current = self._head
        while current:
            yield current
            current = current.next