def remove_empties(list1):
    """removes any empty lists from our list"""
list2 = [x for x in list1 if x]
return list2

def merge_to_couples(new_list):
    answer = []
new_list = remove_empties(new_list)
while True:
    answer.append([new_list[0][0], new_list[1][0]])
del new_list[0][0], new_list[1][0]
new_list = remove_empties(new_list)
if len(new_list) == 0:
    return answer
if len(new_list) == 1:
    for i in new_list[0]:
        answer.append([i])
return answer
A_list = [1, 2, 3]
B_list = [4]
C_list = [5, 6, 7, 8]
D_list = [9, 10]
new_list = [A_list, B_list, C_list, D_list]
print(merge_to_couples(new_list))
Making 4 lists into a 2 element nested list