input: Write a Python function that filters out odd numbers from an input list.
  assert remove_odd([1,2,3]) == [2]
  assert remove_odd([2,4,6]) == [2,4,6]
  assert remove_odd([10,20,3]) == [10,20]
output: def remove_odd(lst):
      return [x for x in lst if x % 2 == 0]