input: Write a function to perform linear search on a given array of strings to find the position of a specified item. If the item is found, return its position; otherwise, return -1. 
  assert linearSearch('hospital') == 1
  assert linearSearch('mall') == 3
  assert linearSearch('library') == -1
  assert linearSearch('school') == 0
  assert linearSearch('theatre') == 4
output: def linearSearch(item):
      array = ['school', 'hospital', 'office', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == item:
              return i
      return -1