input: from typing import List
  
  def linearSearch(search_item: str) -> int:
      """Performs a linear search on a predefined array to find the position of the search item.
      If the search item is not found, it returns -1.
      >>> linearSearch('hospital')
      1
      >>> linearSearch('mall')
      3
      >>> linearSearch('library')
      -1
      """
      array = ['school', 'hospital', 'bookstore', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1
output:     array = ['school', 'hospital', 'bookstore', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1