input: Write a python function to perform a linear search in a list of strings.
  assert linear_search(['remote', 'deliver', 'python', 'code'], 'python') == 2
  assert linear_search(['a', 'b', 'c', 'd'], 'd') == 3
  assert linear_search(['apple', 'banana', 'cherry'], 'orange') == -1
output: def linear_search(lst, target):
      for i, item in enumerate(lst):
          if item == target:
              return i
      return -1