STD_5.py

class Node:
    def __init__(self, dataval=None):
        self.dataval = dataval
        self.nextval = None


class SLinkedList:
    def __init__(self):
        self.headval = None

    def listprint(self):
        printval = self.headval
        while printval is not None:
            print(printval.dataval)
            printval = printval.nextval

    def AtBeginning(self, newdata):
        NewNode = Node(newdata)

    def AtEnd(self, newdata):
        NewNode = Node(newdata)
        if self.headval is None:
            self.headval = NewNode
            return
        last = self.headval
        while (last.nextval):
            last = last.nextval
        last.nextval = NewNode

    def Insert(self, val_before, newdata):
        '''Insert method - adding a new node into linked list.'''

        if val_before is None:                  # if there isn't any value before the new node
            print("No node to insert after")    # print info message
            return
        else:
            newNode = Node(newdata)                 # create new node
            newNode.nextval = val_before.nextval    # assign a next value for new node that was a next
                                                    # node of the value before
            val_before.nextval = newNode            # set the next value of the value before to the added node


list = SLinkedList()
list.headval = Node("Mon")

e2 = Node("Tue")
e3 = Node("Thur")
e4 = Node("Fri")
e5 = Node("Sat")
list.headval.nextval = e2
e2.nextval = e3
e3.nextval = e4
e4.nextval = e5

list.AtEnd("Sun")
list.Insert(e2, "Weds")

list.listprint()