Hacktoberfest 4th PR

#Queues
#Functions

front=rear=0
def empty(q):
    if q==[]:
        return True
    else:
        return False
def push(q,value):
    global front,rear
    print('Add:')
    q.append(value)
    if len(q)==1:
        front=rear=0
    else:
        rear+=1
def pop(q):
    global front,rear
    print('Delete:')
    if empty(q)==True:
        print('Underflow!')
    elif front==rear:
        returnvalue=q[front]
        front=rear=0
        q.clear()
    else:
        returnvalue=q[front]
        front+=1
    return returnvalue
def show(q):
    global front,rear
    for i in range(front,rear+1):
        print(q[i],end=' ')
        
#main

ch=0
q=[]
while True:
    print('\n \t \t QUEUE MENU\n Press 0 to Exit\n Press 1 to Add\n Press 2 to Delete\n Press 3 to Show\n Enter Your Choice:')
    ch=int(input())
    if ch==0:
        break
    elif ch==1:
        if len(q)==0:
            n=int(input('Enter First Value:'))
        else:
            n=int(input('Enter Next Value:'))
        push(q,n)
    elif ch==2:
        if len(q)==0:
            print('No Value-Underflow!')
        else:
            delvalue=pop(q)
            print('Deleted value:',delvalue)
    elif ch==3:
       show(q)
    else:
        print('Wrong Choice!')