input: Write a function to remove all instances of a specific value from a list.
  assert remove_value([10, 20, 30, 40, 10], 10)==[20, 30, 40]
  assert remove_value([1, 2, 3, 4, 5], 3)==[1, 2, 4, 5]
  assert remove_value([7, 8, 9, 7, 10], 7)==[8, 9, 10]
output: def remove_value(lst, value):
      return [x for x in lst if x != value]