input: Write a function to implement a linear search to quickly search through a given array. The function should return the position of the search item if found; otherwise, it should return -1. If the array is empty, the function should return -1.
  def linearSearch(array, search_item):
      if len(array) == 0:
          return -1
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'hospital')==1
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'bookstore')==2
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'airport')==-1
  assert linearSearch(['school', 'hospital', 'bookstore', 'mall', 'theatre'], 'theatre')==4
  assert linearSearch([], 'school')==-1
output: def linearSearch(array, search_item):
      if len(array) == 0:
          return -1
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1