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