chaged prefix.py for multiple prefix

[SuyashGupte]

Resolves Issue #24

Description

Returns the number of words with given prefix. Sample Input: hello i am hellslinger and i am ambidextrous hell am Ouptput: hell : 2 ( hello hellslinger ) am : 3 ( am am ambidextrous )

Technical Specifications

Uses concepts for hashing

Screenshots (if required)

How to run

Please list all the steps required to run in details. Preferably specify steps for all platforms.

Checklist

• [X] Code compiles correctly.
• [X] Changes are tested properly.
• [X] Added the README / documentation, if necessary.
• [X] Followed the Contributing guidelines.
• [X] Resolved merge conflicts, if any.