input: Write a python function to extract numbers from a string of comma-separated values.
  assert extract_numbers("1,2,three,4,five,6") == [1, 2, 4, 6]
  assert extract_numbers("10, -20, 30, forty, 50") == [10, -20, 30, 50]
  assert extract_numbers("100,a,b,c,200") == [100, 200]
output: def extract_numbers(s):
      return [int(x) for x in s.split(',') if x.strip().lstrip('-').isdigit()]