def main():
    x = 1 # x represents an int value
    y = [1, 2, 3] # y represents a list 

    m(x, y) # Invoke m with arguments x and y

    print("x is", x)
    print("y[0] is", y[0])

def m(number, numbers):
    number = 1001 # Assign a new value to number
    numbers[0] = 5555 # Assign a new value to numbers[0]

main() # Call the main function