input: Write a function to perform a linear search on a given array to find an item. If the item is found in the array, return its position, otherwise return -1. Consider the following test cases for this function:
  def linearSearch(search_item):
      array = ['school', 'hospital', 'bookstore', 'mall', 'theatre']
      # Loop through array
      for i in range(len(array)):
          # If search item is found, return its position
          if array[i] == search_item:
              return i
      # If item is not found, return -1
      return -1
  
  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', 'bookstore', 'mall', 'theatre']
      for i in range(len(array)):
          if array[i] == search_item:
              return i
      return -1