input: Write a function to perform linear search in Python to quickly search for a given item in a predefined array. The function should return the position of the item if found, otherwise it should return -1. Define the array as ['school', 'hospital', 'bookstore', 'mall', 'theatre'].
  assert linearSearch('hospital')==1
  assert linearSearch('mall')==3
  assert linearSearch('library')==-1
  assert linearSearch('school')==0
  assert linearSearch('theatre')==4
output: def linearSearch(item):
      array = ['school', 'hospital', 'bookstore', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == item:
              return i
      return -1