For this exercise you will be strengthening your page-fu mastery. You will complete the PaginationHelper class, which is a utility class helpful for querying paging information related to an array.

The class is designed to take in an array of values and an integer indicating how many items will be allowed per each page. The types of values contained within the collection/array are not relevant.

The following are some examples of how this class is used:

 1 helper = PaginationHelper([‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘], 4) 2 helper.page_count # should == 2 3 helper.item_count # should == 6 4 helper.page_item_count(0)  # should == 4 5 helper.page_item_count(1) # last page - should == 2 6 helper.page_item_count(2) # should == -1 since the page is invalid 7  8 # page_ndex takes an item index and returns the page that it belongs on 9 helper.page_index(5) # should == 1 (zero based index)10 helper.page_index(2) # should == 011 helper.page_index(20) # should == -112 helper.page_index(-10) # should == -1 because negative indexes are invalid

 1 # TODO: complete this class 2  3 class PaginationHelper: 4  5   # The constructor takes in an array of items and a integer indicating 6   # how many items fit within a single page 7   def __init__(self, collection, items_per_page): 8     self.collection = collection 9     self.items_per_page = items_per_page10       11   12   # returns the number of items within the entire collection13   def item_count(self):14     return len(self.collection)15   16   # returns the number of pages17   def page_count(self):18     if len(self.collection) % self.items_per_page == 0:19       return len(self.collection) / self.items_per_page20     else:21       return len(self.collection) / self.items_per_page + 122     23       24   25   # returns the number of items on the current page. page_index is zero based26   # this method should return -1 for page_index values that are out of range27   def page_item_count(self,page_index):28     if page_index >= self.page_count():29       return -130     elif page_index == self.page_count() - 1:31       return len(self.collection) % self.items_per_page or self.items_per_page32     else:33       return self.items_per_page34         35       36   37   # determines what page an item is on. Zero based indexes.38   # this method should return -1 for item_index values that are out of range39   def page_index(self,item_index):40     if item_index >= len(self.collection) or item_index < 0:41       return -142     else:43       return item_index / self.items_per_page44