python - How to generate lists from a specification of element combinations -

i want generate bunch of lists using combinations of elements specified in form following:

[[10, 20], [30, 40], [50, 60]] 

this means values available first element 10 , 20, values available second element 30 , 40 , on (i've used 2 element options each element brevity; there more that). want use specification generate lists using combinations of these elements (including possibility of not having any), generating following:

[10] [20] [10, 30] [10, 40] [20, 30] [20, 40] [10, 30, 50] [10, 30, 60] [10, 40, 50] [10, 40, 60] [20, 30, 50] [20, 30, 60] [20, 40, 50] [20, 40, 60] 

i feel though itertools used this, i'm not sure how implement algorithm generate lists this. good, general way (i.e. not limited 3 elements 3 hardcoded nested loops, instance) generate lists specification i've shown above?

as attempt, i've got following:

import itertools  element_specifications = [[10, 20], [30, 40], [50, 60]]  lists = [list(list_configuration) list_configuration in list(itertools.product(*element_specifications))]  list_configuration in lists:     print(list_configuration) 

this produces following lists, note misses out on possibilities arise having no element:

[10, 30, 50] [10, 30, 60] [10, 40, 50] [10, 40, 60] [20, 30, 50] [20, 30, 60] [20, 40, 50] [20, 40, 60] 

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edit: i've come following, seems inelegant me:

import itertools  element_specifications = [[10, 20], [30, 40], [50, 60]]  lists = []  length in range(1, len(element_specifications) + 1):     lists.extend([list(list_configuration) list_configuration in list(itertools.product(*element_specifications[:length]))])  list_configuration in lists:     print(list_configuration) 

you can create double-for-loop list comprehension based on solution found:

>>> elements = [[10, 20], [30, 40], [50, 60]] >>> [x in range(len(elements)) x in itertools.product(*elements[:i+1])] [(10,),  (20,),  (10, 30),  (10, 40),  (20, 30),  (20, 40),  (10, 30, 50),  (10, 30, 60),  (10, 40, 50),  (10, 40, 60),  (20, 30, 50),  (20, 30, 60),  (20, 40, 50),  (20, 40, 60)] 

or maybe bit cleaner, using enumerate:

>>> [x i, _ in enumerate(elements) x in itertools.product(*elements[:i+1])]