Data Structures for Integers

http://opendatastructures.org/ods-python/13_Data_Structures_Integers.html

http://opendatastructures.org/ods-python/13_2_XFastTrie_Searching_in.html

http://opendatastructures.org/ods-python/13_3_YFastTrie_Doubly_Logar.html