input: Write a function to perform linear search in a given array and return the position of the search item if found, otherwise return -1. Define the array and use input to get the search item. If the search item is not found, print "Item not found." Otherwise, print the position of the item.
  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', 'office', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1