Number Counter 1.2 - Some strange errors with negative nums!

# By EthPunch
'''
Hi, I'm a beginner with Python and this is one of my first full creations. You basically have a start and a finish integer and the program will count between them. For some reason, anything below -5 drives the program insane. If you know why, then please let me know.
'''
def tuna(testvariable):
    print("\nHey, welcome to EthPunch's Python Number Counter!")
    start = int(input("Please enter the number you wish to start at: "))
    print(start, " - cool. Now enter the number you want to finish at: ")
    end = int(input())
    print("So we're starting at ", start, " and we're ending at ", end, ". Please press '0' to continue, or '1' if you've made a mistake typing.")
    cucumber = int(input())
    if cucumber is 0:
        decider(start, end)
    elif cucumber is 1:
        beef(testvariable)
    else:
        print("Hey, it looks like you didn't enter a correct number. Let's go back to the beginning.")
        beef(testvariable)

def beef(testvariable):
    tuna(testvariable)

def decider(start, end):
    if start < end:
        NormalCounter(start, end)
    elif end < start:
        backwardsCounter(start, end)
    elif start is end:
        samesame(start)

def NormalCounter(start, end):
    end = end + 1
    for bacon in range(start, end):
        print(bacon)
    print("Done :)")

def backwardsCounter(start, end):
    cheese = True
    num = start
    while cheese is True:
        print(num)
        num = num - 1
        if num is (end - 1):
            print("Done :)")
            break
        else:
            continue
def samesame(start):
    print("Are you trying to trick me? Because I'm not counting from ", start, " to ", start, ".\nI'm gonna go eat some beef and we'll start again.")
    beef(testvariable)

def testFunction():
    print("testFunction seems to be working")

testvariable = 123
tuna(testvariable)