input: Write a function to remove an element from a list by index.
  assert remove_index([1, 2, 3, 4, 5], 2) == [1, 2, 4, 5]
  assert remove_index([10, 20, 30, 40, 50], 0) == [20, 30, 40, 50]
  assert remove_index(['a', 'b', 'c', 'd'], 3) == ['a', 'b', 'c']
output: def remove_index(lst, index):
      return lst[:index] + lst[index+1:]