input: Write a function to implement a linear search on a given array. The function should take an item as input and return its position if found in the array, otherwise it should return -1. If the array is empty, the function should return -1.
  assert linearSearch("hospital") == 1
  assert linearSearch("mall") == 3
  assert linearSearch("zoo") == -1
  assert linearSearch("school") == 0
  assert linearSearch("") == -1
output: def linearSearch(item):
      array = ["school", "hospital", "store", "mall"]
      if not array:
          return -1
      for i in range(len(array)):
          if array[i] == item:
              return i
      return -1