input: Write a function to create a linear search engine in Python that searches through a given array. The function should return the position of the item if found, otherwise return -1. If the input array is empty, the function should return -1.
  
  def linearSearch(array, search_item):
      # Loop through array
      for i in range(len(array)):
          # If search item is found, return its position
          if array[i] == search_item:
              return i
      # If item is not found, return -1
      return -1
  
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'bookstore') == 2
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'theatre') == 4
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'park') == -1
  assert linearSearch([], 'mall') == -1
output: def linearSearch(array, search_item):
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1