def add_spam(menu=[]):
    menu.append("spam")
    return menu
    

breakfast  =  ['bacon',  'eggs']
add_spam(breakfast)

lunch  =  ['baked  beans']
add_spam(lunch)

#Using the default parameter
add_spam()
add_spam() 
add_spam()
add_spam()


#Fxing the issue
def add_spam(menu=None):
    if menu  is None:
        menu = []
    menu.append('spam')
    return menu


add_spam() 
add_spam() 
add_spam()
