linked_list.py

class Link:
    def __init__(self):
        self.value = None
        self.nextLink = None

    def setValue(self, value):
        self.value = value

    def setNext(self, nextLink):
        self.nextLink = nextLink


head = Link()

head.setValue(1)
head.setNext(None)

current = head

for i in range(2, 21):
    newLink = Link()
    newLink.setValue(i)
    newLink.setNext(head)
    current.setNext(newLink)
    current = newLink

current = head

for i in range(0, 21):
    print(current.value)
    current = current.nextLink