#Python program to generate all sublists of a list 
def sub_lists(my_list):
    subs = [[]]
    for i in range(len(my_list)):
        n = i+1 
        while n <= len(my_list):
            sub = my_list[i:n]        
            subs.append(sub)
	    n += 1 
    return subs 

l1 = [10,20,30,40]
l2 = ['X', 'Y', 'Z']
print(sub_lists(l1))
print(sub_lists(l2))
