input: Write a python function to find negative numbers in a list.
  assert find_negatives([1, -2, 3, -4, 5, -6, 7, 8, -9, 10])==[-2, -4, -6, -9]
  assert find_negatives([10, -20, 45, -67, 84, -93])==[-20, -67, -93]
  assert find_negatives([5, 7, -9, 8, 6, 4, -3])==[-9, -3]
output: def find_negatives(lst):
      return [x for x in lst if x < 0]