def modify_list(lst,i,val):
	"""assign val to lst[i]
        does not return any value"""
	if len(lst)>i:
		lst[i]=val
	return None

def nullify(lst):
    lst=[]
#no value returned

def nullify_pr(lst):
    print(hex(id(lst)))
    lst=[]
    print(hex(id(lst)))
#no value returned