input: Write a function to create a simple linear search engine in Python to search through a given array of strings. If the search item is found in the array, return its position. If the item is not found in the array, return -1. Provide the function with necessary input and output handling.
  assert linearSearch('mall')==3
  assert linearSearch('bookstore')==2
  assert linearSearch('park')==-1
  assert linearSearch('theatre')==4
  assert linearSearch('school')==0
output: def linearSearch(item):
      array = ['school', 'bookstore', 'bookstore', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == item:
              return i
      return -1