input: from typing import List
  
  def linear_search(arr: List, x: int) -> int:
      """Search for an element in a list using linear search. If found, return the index, otherwise return -1.
      >>> linear_search([1, 2, 3, 4], 2)
      1
      >>> linear_search([1, 2, 3, 4], 5)
      -1
      """
      for index, item in enumerate(arr):
          if item == x:
              return index
      return -1
output:     for index, item in enumerate(arr):
          if item == x:
              return index
      return -1