input: Write a function to generate all possible sums of elements from two lists using list comprehensions.
  assert generate_sums([1, 2, 3], [4, 5, 6]) == [5, 6, 7, 6, 7, 8, 7, 8, 9]
  assert generate_sums([0, 1], [2, 3]) == [2, 3, 3, 4]
  assert generate_sums([1], [10, 20, 30]) == [11, 21, 31]
output: def generate_sums(list1, list2):
      return [x + y for x in list1 for y in list2]