Implement an autocomplete system. That is, given a query string s and a dictionary of all possible query strings, return all strings in the dictionary that have s as a prefix.
Hint: Try pre-processing the dictionary into a more efficient data structure to speed up queries.
Example:
>>> words = ['able', 'abode', 'about', 'above', 'abuse', 'syzygy']
>>> coding_problem_11(words, 'abo')
['abode', 'about', 'above']