input: Write a function to remove common elements from two lists.
  assert remove_common_elements([10, 15, 20, 25, 30, 35, 40], [25, 40, 35]) == [10, 15, 20, 30]
  assert remove_common_elements([1, 2, 3, 4, 5], [2, 5]) == [1, 3, 4]
  assert remove_common_elements([7, 8, 9], [8, 9, 10]) == [7]
  assert remove_common_elements([1, 2, 3], [4, 5, 6]) == [1, 2, 3]
output: def remove_common_elements(list1, list2):
      return [item for item in list1 if item not in list2]