input: Write a function to create a search engine in Python that performs a linear search in a given array. If the search item is found, return its position; otherwise, return -1. The function should take a search item as input and return the position of the item in the array or -1 if the item is not found.
  assert linearSearch('hospital')==1
  assert linearSearch('mall')==3
  assert linearSearch('library')==-1
  assert linearSearch('school')==0
  assert linearSearch('theatre')==4
output: def linearSearch(search_item):
      array = ['school', 'hospital', 'school', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1