Write a function to compute the sum of digits of each number of a given list.
def sum_of_digits(nums):
    return sum(int(el) for n in nums for el in str(n) if el.isdigit())
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to compute the sum of digits of each number of a given list.
def sum_of_digits(nums):
    return sum(int(el) for n in nums for el in str(n) if el.isdigit())[/INST]assert sum_of_digits([10,2,56])==14
assert sum_of_digits([[10,20,4,5,'b',70,'a']])==19
assert sum_of_digits([10,20,-4,5,-70])==19</s>