Dictionary module implements the so called hash table, or a hash map.
A Dictionary means a data structure that associates keys with values. The primary operation it supports efficiently is a lookup: given a key (e.g. a person's name), find the corresponding value (e.g. that person's telephone number). It works by transforming the key using a hash function into a hash, a number that is used to index into an array to locate the desired location ("bucket") where the values should be.
How to use this module
Inside your script, before calling any module specific keyword, add the following:
More information about hash tables can be found here: http://en.wikipedia.org/wiki/Hash_table