######################################################################
# Class definitions
######################################################################

class LinkedList():
    __slots__ = ("head","size")

class Node():
    __slots__ = ("data", "next")

######################################################################
# Class builders
######################################################################

def mkLinkedList():
    """Builder: mkList: () -> LinkedList"""
    lst = LinkedList()
    lst.head = None
    lst.size=0
    return lst

def mkNode( data, lst ):
    """Builder: Node -> Node"""
    node = Node()
    node.data = data
    node.next = lst
    return node

######################################################################
# Function definitions
######################################################################

def display( lst ):
    pass

def size( lst ):
    pass

def get( lst, pos ):
    pass

def getItr(l1):
    pass

def nxt(itr):
    pass

def hasNxt(itr):
    pass

def isEnd(itr):
    pass
    
def index( lst, ele ):
    pass

def append( lst, ele ):
    pass
            
def insert( lst, ele, pos ):
    pass

def remove( lst, pos ):
    pass


######################################################################
# test function definitions
######################################################################

def initTestLists():
    l1 = mkLinkedList()

    l2 = mkLinkedList()
    append(l2,"p")

    l3 = mkLinkedList()
    append(l3,'a')
    append(l3,'b')
    append(l3,'c')

    return l1,l2,l3

def printTest(l1,l2,l3):
    print("list1: ", end="" )
    display( l1 )
    print("list2: ", end="" )
    display( l2 )
    print("list3: ", end="" )
    display( l3 )
    print("=========================")

def test():
    l1,l2,l3 = initTestLists()
    print("size l1=",size(l1))
    print("size l2=",size(l2))
    print("size l3=",size(l3))
    printTest(l1,l2,l3)
    
    l1,l2,l3 = initTestLists()
    print("get l2 #0",get(l2,0))
    print("get l3 #0",get(l3,0))
    print("get l3 #1",get(l3,1))
    print("get l3 #2",get(l3,2))
    printTest(l1,l2,l3)

    l1,l2,l3 = initTestLists()
    print("index l1 'b'",index(l2,"b"))
    print("index l2 'p'",index(l2,"p"))
    print("index l2 'a'",index(l2,"a"))
    print("index l3 'a'",index(l3,"a"))
    print("index l3 'b'",index(l3,"b"))
    print("index l3 'c'",index(l3,"c"))
    print("index l3 'p'",index(l3,"p"))
    printTest(l1,l2,l3)
    
    l1,l2,l3 = initTestLists()
    append(l1,"Z")
    append(l2,"Z")
    append(l3,"Z")
    printTest(l1,l2,l3)
    
    l1,l2,l3 = initTestLists()
    insert(l1,"Z",0)
    insert(l1,"Y",0)
    insert(l2,"Z",1)
    insert(l3,"P",1)
    insert(l3,"Z",4)
    printTest(l1,l2,l3)

    l1,l2,l3 = initTestLists()
    print("remove l2 #0",remove(l2,0))
    print("remove l3 #0",remove(l3,0))
    print("remove l3 #0",remove(l3,0))
    print("remove l3 #0",remove(l3,0))
    printTest(l1,l2,l3)

    l1,l2,l3 = initTestLists()
    print("remove l3 #1",remove(l3,1))
    print("remove l3 #1",remove(l3,1))
    print("remove l3 #0",remove(l3,0))
    printTest(l1,l2,l3)

"""
if __name__ == "__main__":
    test()
"""
n3 = mkNode('c',None)
n2 = mkNode('b',n3)
n1 = mkNode('a', n2)
display(n1)
print("length of n1 is", size(n1))